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A Field Survey Manual for Vertebrates A Field Survey Manual for Vertebrates Edited by Glyn Davies Edited by Glyn Davies

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A Field Survey Manual for VertebratesA Field Survey Manual for Vertebrates

Edited by Glyn DaviesEdited by Glyn Davies

Earthwatch supports field research projects in over 40 countries aroundthe world, in a wide range of disciplines and habitats. The organisation hassupported research in African tropical forests for over 20 years, and acceptsapplications for funding from researchers across the continent.

Earthwatch Europe runs a professional development programmedesigned to build the capacity of African institutions working to conservebiodiversity. Our African Fellowship Programme places African conservationists,scientists and NGO workers on field research projects relevant to theirprofessional lives. The programme provides training in an African context;through the unique experience of practical participation on a project in anotherAfrican country, and working in an international team with other Africanconservation professionals from across the continent.

Publication of this manual has been made possible through agenerous donation from Rio Tinto plc.

African Forest Biodiversity:a field survey manual for

vertebratesEditor Glyn Davies

Assistant Editor Michael Hoffmann

Authors

Leon Bennun*Department of Ornithology

National Museums of KenyaP O Box 40658

NairobiKenya

Glyn DaviesZoological Society of London

Regents ParkLondon NW1 4RY

UK

Kim HowellDepartment of Zoology and Marine Biology

University of Dar es SalaamP O Box 35064Dar es Salaam

Tanzania

Helen NewingDurrell Institute of Conservation and Ecology

University of Kent at CanterburyCanterbury

Kent CT2 7NSUK

Matthew LinkieDurrell Institute of Conservation and Ecology

University of Kent at CanterburyCanterbury

Kent CT2 7NSUK

Illustrations by John Clarke

*Current Address: Birdlife International, Wellbrook Court, Girton Road, Cambridge, CB3 0NA, UK

Published in the UK in 2002 by Earthwatch Europe.

ISBN 0-9538179-4-6

Publisher’s reference: 141-04-02

© Copyright Earthwatch Institute (Europe) and contributors 2002.All rights reserved. The use and reproduction of any part of this publication is welcomed for non-commercial purposes only, provided that the source is acknowledged.

This publication was funded by the EC Tropical Forests budget line. The authors are solelyresponsible for all opinions expressed in this document, which do not necessarily reflect those ofthe European Union.

Printed by Seacourt Press, who hold ISO 14001 and EMAS environmental certifications, usingwaterless printing and vegetable-based inks on chlorine free part-recycled paper.

Earthwatch Institute (Europe) is a self-governing and self-financing charity (Registered Number327017) operating under English law with an independent Board of Trustees, and is affiliated with aglobal organization led by Earthwatch Institute in the US from and through which EarthwatchInstitute (Europe) obtains a variety of goods and services including the right to use the Earthwatchname and access to the Earthwatch international program of field projects.

®

AcknowledgementsThis manual has benefitted from discussions and the reports from two

forest survey workshops: Kakamega, Kenya (1995) and Limbe, Cameroon(1996). This restructured and rewritten document has been improved withhelpful comments and advice from: Tom Butynski, Tim Davenport, Rob andCheryl Fimbel, Frank Hawkins, Dwight Larsen, Martyn Murray, John Oates,Andy Plumptre, and Justina Ray. I am grateful to all of them for their time andassistance. I am indebted to all the authors, who have stuck at this throughthick and thin, and to John Clarke whose plates have greatly enhanced thevisual image of the document.

Mike Hoffmann came to our aid with the final compilation and editing,and Sylvia Howe assisted with the design, layout and proof reading. JulianLaird (Earthwatch Europe) has steadfastly supported the production of thisdocument following a visit to Limbe in 1997, and we acknowledge the financialsupport of the EC Tropical Forests budget line and Rio Tinto plc.

Glyn DaviesEditor

Main cover photograph by Glyn Davies. Side bar photographs by Glyn Davies, except bottom photographcourtesy of Marcus Rowcliffe.

Contents1. Introduction

1.1 Background 11.2 Scope of the Manual 21.3 Structure and content 3

2. Forest Surveys2.1 What is forest biodiversity? 52.2 Forest management 72.3 Research into forest biodiversity 92.4 Ethical and legal standards 112.5 Preparations 112.6 A note on market surveys

and questionnaires/ interviews 142.7 Health and safety 152.8 References 16

3. Amphibians and reptiles: herptiles3.1 Biology 173.2 Management issues 183.3 Methods 19

3.3.1 General surveys 213.3.2 Drift fences and pitfall traps 233.3.3 Canopy walkway trap 273.3.4 Snake trapping 293.3.5 Capture, mark, recapture 313.3.6 Forest litter plots 313.3.7 Time-constrained searches 333.3.8 Transect counts 343.3.9 Territory mapping 343.3.10 Sound recording surveys 35

3.4 Specimen handling 363.5 Health and safety 373.6 Conclusions 383.7 References 39

4. Small mammals: bats, rodents and insectivores 4.1 Biology 454.2 Management issues 474.3 Methods 48

4.3.1 General surveys 494.3.2 Bat roost surveys 494.3.3 Live-trapping: rodents and insectivores 504.3.4 Live-trapping: bats 544.3.5 Capture, mark, recapture 584.3.6 Removal or dead-trapping 59

4.4 Specimen handling 604.5 Health and safety 644.6 Conclusions 644.7 References 65

5. Large and medium-sized mammals5.1 Biology 695.2 Management issues 705.3 Methods 72

5.3.1 Hunters’ calls, attractants and observation points 735.3.2 Net drives 755.3.3 Survey walks: reconnaissance surveys

and transect 775.3.4 Indirect methods 82

A. Dung counts 82B. Track (footprint) surveys 86C. Photo-recording 90

5.4 Conclusions 925.5 References 92

6. Primates6.1 Biology 996.2 Management issues 1026.3 Methods 104

6.3.1 Distribution surveys 1056.3.2 Line transects 106

A. Animal sightings 107B. Nest counts 110C. Mapping calls 111

6.3.3 Sweep surveys 1146.4 Conclusions 1166.5 References 116

7. Birds7.1 Biology 1217.2 Management issues 1247.3 Methods 126

7.3.1 General surveys 1307.3.2 Timed species-counts (TSCs) 1317.3.3 MacKinnon lists and related methods 1347.3.4 Timed transects (TTs) 1367.3.5 Fixed-width transect counts 1367.3.6 Fixed-width point counts 1387.3.7 Distance sampling 1407.3.8 Mist netting and ringing 1417.3.9 Sound recording 1477.3.10 Territory mapping 1497.3.11 Special considerations 149

7.4 Specimen handling 1517.5 Health and safety 1527.6 Conclusions 1527.7 References 154

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1.1 BackgroundThis manual is the product of many years of forest survey experience,

and is based upon discussions between field workers about ways that surveyscan be improved and standardised.

The first steps towards producing this manual were taken at the 4th EastAfrican Regional Database workshop, held in Kampala in August 1993, whenparticipants expressed an urgent need for guidelines that would allow standard-isation of field methods for forest biodiversity surveys. In response, theregional Global Environment Facility (GEF) Project (Institutional Support for theProtection of East African Biodiversity) agreed to fund a training workshop, aspart of its Conservation and Management of Closed Forests programme. Thisworkshop was held in Kakamega Forest Reserve and Mount Elgon NationalPark, Kenya in November 1994, and led to the production of a workshopreport/training manual titled Guidelines for Forest Biodiversity Inventories(1995:UHNO/RAF/006/GEF).

Two years later, at another GEF-supported workshop in Limbe BotanicGarden, Cameroon, many of the same forest survey issues were discussed inthe context of the Central African region (March 1996). Another workshopreport was produced at this meeting: Protocols for Biological Surveys inCameroonian Forests.

1. IntroductionGlyn Davies

Although both workshop reports served their immediate purposes ofrecording conclusions of survey experience, there were frequent requests(often from isolated project managers and field staff) for copies of the docu-ments long after the workshops had finished. Because the obvious conclusionfrom both of these documents was that many of the survey methods could beapplied in the field in both forest regions, the requests prompted the currentcollaborative effort to produce a forest survey field manual that would bedistributed widely.

1.2 Scope of the manualThis manual concentrates only on forest vertebrates, excluding fish.

The Kakamega and Limbe workshops focused on surveys of a much widerspectrum of forest fauna and flora, and attention was also given to socio-eco-nomic survey methods. It was beyond the resources of those involved in theproduction of this manual to cover this full range of subjects, but it is hopedthat future survey manuals can be produced to cover them.

Two excellent series that describe survey methods for single taxonomicgroups are the comprehensive Measuring and Monitoring Biodiversity series,produced by the Smithsonian Institution (Washington, USA), and the less-detailed Expeditions Field Techniques series by the Royal GeographicalSociety (London, UK). Furthermore, an excellent technical handbookConservation Research in African Rainforests (White & Edwards, 2000) hasrecently been published, which focuses on vegetation and large mammalsurveys in central Africa.

This manual differs in that it moves away from the single taxonomicgroup approach, and considers the full range of vertebrates found in Africanforests. By so doing, we hope to raise awareness about the possibilities of car-rying out surveys of several taxonomic groups at a given forest site. This doesnot preclude surveys focusing on particuar groups; but does encourage datagathering on other species (see general surveys in each chapter).

The target audience for the manual comprises four main groups:� people carrying out short reconnaissance surveys and expeditions;� undergraduate and graduate students carrying out project

and thesis work;� research departments of forest, wildlife and national parks

departments;� forest and wildlife managers and technicians with responsibility

for monitoring biodiversity.

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Enlightened forest management requires information about a broadrange of species, and time is too short, and resources too limited, for all forestareas to be considered by separate specialist survey teams. By explaining therange of methods available to gather information on biodiversity issues, forestmanagers and planners will be aware of how information is gathered, and sofeel better equipped to include biodiversity in their work.

The primary aim of the manual, therefore, is to provide an overview ofthe methods that can be used to gather information needed for effective man-agement of African forests, which takes full account of all vertebrates as acomponent of forest ecosystem biodiversity.

An important extension of this aim is to encourage surveyors andresearchers to use standardised methods so that survey results can be used tomonitor change over time, whether changes are positive as a result of manage-ment interventions or negative as a result of unsustainable use or clearance.Long-term monitoring usually involves different surveyors, as people changejobs or move, and each set of new observers/surveyors should use the samemethods if the results are to be comparable. While focusing attention on thisneed for standardised methods, it is understood that methods continue to beimproved, and different forests, survey team resources, and managementquestions will all require adaptation of the standard techniques.

Finally, the manual is intended as a field companion, and as a trainingtool for students, at college and university, and in forest and wildlife services.However, this manual is not a field identification guide and the relevant identifi-cation guides will be needed.

1.3 Structure and contentChapter 2, Forest Surveys, gives a brief introduction to forest biodiversity

and management, and the need for research as a tool in managing forest bio-diversity. In addition, it includes introductory notes on ethical and legal stan-dards, preparations for carrying out surveys, and notes on health and safety.

Chapters 3 to 7 cover the survey methods according to each respectivegroup of animals. Each chapter includes sections on the biology and manage-ment issues of the relevant group, the various survey methods, followed bypointers on specimen handling and, in some cases, additional notes on healthand safety. Each chapter concludes with a list of references. To ease refer-ence, the survey methods discussed in these chapters have been organised tofollow generally similar headings giving: additional/special equipment or per-sonnel required (see 2.5); site selection (where pertinent); procedure;processes of recording; data analysis; and an assessment of the advantagesand limitations of the methods. To avoid unnecessary repetition, certain

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sections have not been duplicated in each chapter, in which case the readerwill be referred to the relevant section in another chapter. However, readers areadvised to read the introductory sections of all chapters because differentauthors have stressed different issues – all of which are important whateverspecies group is being surveyed.

The manual can be carried into the field to guide survey work, in order toensure that the right information is gathered for subsequent analysis and reportwriting. It is beyond the scope of this manual to provide details of the statisticaltests or analyses required to analyse and interpret field survey resultsaccurately. Instead, such texts are referenced in the chapters (including theSmithsonian series and White & Edwards (2000)), and these should be con-sulted in conjunction with this manual. Sample survey forms, which can bephotocopied for use in the field, are included at the back of each chapter.

Given the background, some chapters put stronger emphasis on forestsin eastern Africa, and others on western and central Africa. However, the sur-vey methods described, and the principles that need to be followed, apply in allforest surveys in Africa, in Madagascar, and, indeed, even on other continents.

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2. Forest SurveysGlyn Davies

2.1 What is forest diversity?

Biodiversity is the wealth of all life on earth, which can be considered atthree inter-linked levels: genetic, species and ecosystem (see Box 1).

Biodiversity is ‘... the variability among living organisms from allsources, including, inter alia, terrestrial, marine and other aquatic ecosystemsand the ecological complexes of which they are part; this includes diversitywithin species, between species and of ecosystems.’ (Article 2, Conventionon Biological Diversity, 1992).

Forest biodiversity can also be considered in terms of composition,structure and function, and generally is characterised by:

� very high species richness – 50% of all terrestrial species in theworld are found in rain forests;

� multi-layered structure, with giant emergent trees, forest floor herbs, epiphytic herbs and woody lianas, and a correspondingly dark understorey;

� often infertile soils and rapid recycling of plant and soil nutrients;� long timescales over which patterns of regeneration and

reproduction take place.

Measuring forest biodiversity must therefore take account of thesecharacteristics, and pay attention to different species’ qualities, sometimestermed ‘bioqualities’ – are they common, forest-dependent, rare, insectivorous,medicinal plants, marketable timber, and so on? With such a range of featuresto consider, and a lack of detailed ecological information on many forestspecies, it is inevitable that surveys have often focused on a number of indica-tor species in an area as a first approximation of forest biodiversity (Noss,1990). But this raises the question of which species to select for surveys.

One obvious approach is to focus on one, or a set of, key species inrelation to a particular management question, such as over-exploitation of amedicinal plant, or the unsustainable trapping of large mammals. By monitor-ing these ‘threatened’ species, and ensuring that their use is managed in asustainable way, other forest plant and animal groups may also benefit. This isnot automatically the case, because species-specific threats may not apply toall groups; for example, small birds are unlikely to be affected by the hunting oflarge mammals, and timber trees will continue to stand long after medicinalherbs have been lost. But monitoring the impacts of threats is an important firststep in improving forest management.

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Box 1: Levels of biodiversity

� Genetic biodiversity refers to the frequency and variety of genesand/or genomes within, and between, populations of the same

species, and the information contained within these genes providesthe basis for evolution through adaptation. Examples of genetic biodi-versity are reflected in the different coat colours of mona monkeys,Cercopithecus mona, or in the yields of a plantation tree species.

� Species biodiversity refers to the number and abundance of speciesin an area, and the extent to which species differ in their geneticmake-up. It incorporates characteristics such as taxonomic unique-ness, size and structure, population dynamics, reproductive cycles andbehaviour patterns.

� Ecosystem biodiversity is reflected in the definition of an ecosystem:‘...a dynamic complex of plant, animal and micro-organism communi-ties and their non-living environment, interacting as a functional unit.’(Convention on Biological Diversity). The interplay between speciesincludes pollination, predation, parasitism and symbiosis, while theinteraction between species and their non-living environment includessoil formation, photosynthesis etc. Ecosystems and human culturehave influenced each other over the millennia, giving rise to productivelandscapes that combine biological and cultural diversity.

A similar approach applies when surveys focus on species that areknown to be rare, on the basis that if conditions are suitable for the rarest for-est species, then commoner forest species will probably have healthy popula-tions. However, the current and past causes of rarity vary greatly, and there-fore limit the usefulness of rare species as indicators. Nonetheless, if a num-ber of nationally or globally rare species are present then the condition of theforest ecosystem is likely to be good.

To assess the impacts of forest habitat change across a wider range ofspecies, a set of indicator species are often selected from (a) particular taxo-nomic group(s) about which there is a good body of taxonomic and ecologicalknowledge. For example, changes to a forest habitat have been shown toinfluence the population densities of forest-specialist bird species (e.g.Newmark, 1991), and the factors that have caused their decline may also affectforest specialists in other taxonomic groups. But we need to research whether‘sensitive’ species in different taxonomic groups all respond in the same way tothe same changes in the forest ecosystem. Pending such an investigation,caution is necessary before extrapolating impacts of forest change from oneindicator group to another.

Besides being cautious about the use of indicator species, care isneeded with regard to the seasons and timescale over which surveys are car-ried out. In some seasons, species may be easier or harder to locate becauseof particular behavioural traits: breeding, migration, food abundance and so on.To get year-round data, surveys need to be carried out in different seasons.Furthermore, long timescales need to be used if ecosystem functions are to bemonitored, because the impact of species declines on other processes maytake a considerable time before they are felt. For example, some trees whoseseeds are dispersed by elephants may decline over decades as a result of theelimination of large mammals by hunters.

2.2 Forest managementFrom the outset, it is important to stress that conservation and sustain-

able use of forests can only occur if forest habitat is maintained. Forest covercan include indigenous, naturally regenerating forest, and planted/managedforests of indigenous or exotic species. Trees planted on farms are also impor-tant for biodiversity, especially where they act as corridors connecting differentforest patches. However, having emphasised this basic point, not all types offorest are equally important for the maintenance of biodiversity.

Most of the natural forests in Africa face pressure from communities whoderive their basic livelihood from forests, or the land on which they grow, andeven greater pressure comes from commercial plantation companies and

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extractors of timber and other products. Conflicts often occur as a result ofcompetition for forest resources from local people’s livelihoods, commerce,wildlife and forestry, and the alarming rate of biodiversity loss in African forestsposes an international concern.

International and national discussions and processes, such as thenational Tropical Forest Action Plans, the UN Forum on Forests and theInternational Timber Trade Organization, have all been developed to addressthis problem. These processes are mirrored by the conferences of theConvention on Biological Diversity, and its related Biodiversity Strategies andAction Plans, which include decisions on forest biodiversity.

While these international policy processes evolve, there is a pressingneed to address the conflicts on the ground, and inform policy debate withappropriate information on the range of uses that forests can fulfil. Also, it is atthe field level that decisions need to be taken, by the owner/steward of a forestarea, on the management aims for forest areas.

Developing and implementing forest management plans through consul-tation processes, involving civil society (especially local communities), govern-ment and the private sector, allows different forest users’ needs to be takeninto account. The management plan can then include actions to prevent dam-age to ecological services, and limit loss of genes, species and forest habitats,while forests continue to supply important goods and services. Drawing up

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Box 2: Examples of forest management aims

� Ensure high quality fresh water at acceptable flow-rates, minimiseerosion and movement of soil, and stabilise hillsides, through forestmanagement in watersheds.

� Conserve a representative sample of a biological region (province, biome or habitat) in a state relatively unaltered by modern man, and avoid the loss of species and erosion of genetic diversity.

� Maintain areas and features that are essential for ecologicalprocesses, such as migrations and biological cycles, andrehabilitate degraded areas.

� Protect sites of cultural or archaeological importance.� Ensure the supply of wood and non-wood products to satisfy

local/national/international demand.� Provide facilities and opportunities for tourism, recreation,

environmental education, research and monitoring.� Retain a maximum choice of land-use options for the future.

multiple-use management plans to address this range of issues requires anumber of different types of information.

It is the responsibility of those carrying out biodiversity surveys to pre-sent their results in a form that can be understood by people interested inmanaging the forest (not just technicians and scientists), so that social,economic and biological information can be integrated, and the informationunderstood by local people, government and private enterprise.

The results also need to show the links between the details of forestresource availability, and the bigger picture of national or regional patterns offorest use and national development. Survey questions should be guided byinformation from household surveys on patterns of forest use, and market sur-veys of commercial patterns of use, road-side sales, bushmeat markets, and soon (see section 2.6). The links between in-forest and out-forest data collectionneed to be carefully considered.

2.3 Research into forest biodiversityCarrying out the forest surveys described in this manual will help identify

research needs, and the results of these surveys should also provide the firststeps in answering many research questions. Although time is one of thegreatest restrictions on surveys, it is important to note that data becomes morerobust as it accumulates over days, weeks, months and years. This manualfocuses on getting started, so that the presence/absence of species can beassessed, and the relative abundance of some of the commoner and

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Box 3: Sets of information needed for forest management planning

� Physical features: location; area; altitude; topography and drainage;infrastructure (including villages); climate.

� Biological resources: biodiversity; abundance and yields of commer-cial species.

� Social, policy and legal framework: the population density, with anassessment of the proportion and distribution of indigenous, local andrecently arrived groups; patterns of forest use by different groups; andnational and traditional laws relating to land ownership, forest use andmanagement, and their effectiveness.

� Economic context: what economic policies and market forces are influencing the rates at which different forest resources (including forested land) are being used?

more conspicuous species gauged. For more thorough ecological monitoring,poor visibility in forests requires that a great deal of time and effort be expend-ed before reliable results can be obtained (e.g. Walsh & White, 1999; Plumptre,2000; White & Edwards, 2000).

Perhaps one of the most important constraints to gathering useful infor-mation for multiple-use management is that inter-disciplinary research teamsare few, and there has been little investment in developing research or surveymethods that integrate biological, social and economic information. This is akey area of research that needs to build upon the foundations laid by ethno-biological and socio-economic studies, so that the interests of different stake-holders can be included in planning processes. This is especially true for thoseindigenous and local communities that already possess a wealth of knowledgeabout biodiversity and its management.

There are precedents for carrying out participatory forest surveys, wherelocal specialists plan and implement surveys, in collaboration with other parties,to agree on resource abundance, or to monitor patterns of forest use. Indeed,programmes for training ‘para-taxonomists’ have been developed, in whichlocal experts are given training which enables them to integrate their knowledgewith scientific and technical information. In this context, it is important that allfieldwork conforms to international standards on ethical and legal practice inthe field (see below), respecting local knowledge.

Immediate priorities for applied research include developing surveymethods that can be used for rapid, problem-oriented inventories and monitor-ing. One of the subsidiary aims addressed in this manual is to focus attentionon the need for more biodiversity information to be incorporated intoEnvironmental Impact Assessment (EIA) checklists for forests in Africa. Todate, little has been done to develop biodiversity criteria or indicators that canbe used to assess or monitor impacts of road-building, agriculture and otherdevelopments on forest biodiversity in adjacent areas.

While answering these pressing management questions, pure researchinto forest biodiversity continues to be vital, and many of the summary state-ments about ecology that are made in the chapters that follow are based onlong-term and meticulous research efforts. Furthermore, the information accu-mulated at long-term sites, with well-studied populations, is essential for cali-brating results from rapid surveys with known population figures. We still needresearch to understand what controls plant and animal population densities,and what elements of plant–animal interactions are central to maintaininghealthy forest ecosystems. In addition, continued research in the field oftaxonomy is necessary to ensure that accurate and consistent species namesare attributed to field records.

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2.4 Ethical and legal standardsWhether field activities are short or long-term surveys, and whether car-

ried out by national or visiting scientists, international standards of ethical andlegal practice need to be followed (e.g. Fauna & Flora International, 2000).These have been compiled by a number of institutions, especially those con-cerned with anthropological work, and the reader should refer to the full texts ifthere is any uncertainty about planned actions. In general, care needs to betaken:

� to ensure that official research permits, including collecting permitsand equipment import licences, have been provided, and that asponsoring national institution has approved and supports the pro-posed survey work. Also ensure that any products that arise fromthe work (including reports, books, scientific papers, films, etc.)acknowledge the sponsoring institution, and provide copies to themand other government departments.

� to endeavour to work with and through local institutions, buildingfrom their capacity and taking their advice. Wherever possible con-tribute to building local capacity. When employing local field assis-tants ensure that local labour codes are respected.

� to collect animal specimens in a humane and ethical manner, with as few specimens collected as necessary to satisfy scientific needs, and with the absolute minimum amount of pain or suffering inflicted upon the animal.

� to take account of beliefs, customs and rights of local communities, and guard against the appropriation of their intellectual property.

2.5 PreparationsSuccessful surveys require careful planning and preparation. In particu-

lar, you must think carefully about the purpose and objective of your survey, asthis will determine the information that you need to obtain, and thus themethodology that is most appropriate. In addition, before you start surveying,you need to think how the data will be analysed. This is vital in order todevelop an appropriate sample design. Although detailed discussion of dataanalysis is beyond the scope of this manual, some simple considerations areprovided to help you ascertain whether the chosen method will prove useful forstatistical analysis.

Tips on identification are provided in each chapter. However, it is wellworthwhile spending some time in museums inspecting skins, perusing fieldguides, and taking opportunities to visit field study sites. Through all of these

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methods, and by speaking to knowledgeable people, it is a good idea to startcompiling a species list for the forest sites, or general regions, that will bevisited.

Besides general reference books, atlas projects can provide very usefulindications as to the possible occurrence of a species in a particular area. Forexample, bird atlas projects are underway or completed in a number of coun-tries (for example, the whole of southern Africa, Kenya, Tanzania and Uganda),and a list of species recorded for a particular atlas square (or point, in the caseof Uganda) can usually be produced on request to the coordinators.

As well as being able to identify particular species, many of the surveymethods described here rely on accurate estimation of distances. It is veryimportant to practise distance estimation before you start your work. If you areusing a cut-off point of 25m, for example, go into the forest and estimate thisdistance, then measure to see how accurate your estimation was. Continuepractising until you can estimate this distance reliably in this habitat. Indeed, itis important to practise this in a similar vegetation type to the transects; dis-tances appear very different in the open when compared to dense forest, andstride lengths tend to become much shorter when hopping over logs, runningaway from driver ants, or wading through a swamp. It is crucial that all thosewho are counting are accurate in their distance estimation.

The latter point, namely the discrepancies that result in distance estima-tions as a result of people judging distances differently (see Mitani et al., 2000),argues well for the use of an optical range finder. The reliability and accuracyof optical range finders has made them an invaluable tool in the field, all themore so because all transect methods assume distances are exact. It takes lit-tle time to learn how to use an optical rangefinder properly, and they generallyare inexpensive given the costs of a survey.

Survey equipmentAlthough each chapter makes reference to special equipment and/or

personnel necessary to conduct the individual survey methods, there is somebasic equipment that is common to all surveys and may be considered asessential items to be carried into the field. It goes without saying that suitableclothing, footwear, field bags and camping equipment are basic necessities.

� notebook (with plastic bag for rain protection): many people preferto use a loose-leaf binder, so that only the notes for a particularfield session are taken to the field. Previous notes can then be keptelsewhere for safety, and photocopied as soon as one returns fromthe field session. The importance of keeping duplicate records(either by using carbon paper in the field, or by photocopying), or ofbacking up information electronically, cannot be over-emphasised.

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The advent of hand-held computers or personal data assistants(PDA’s) appears set to revolutionise data input/collection.

� data recording sheets or forms: these can be designed andphoto-copied in advance, or simple formats can be reproduceddaily in a notebook or binder.

� topographic maps of the survey area, on as large a scale asavailable, and map of trails, footpaths, etc. if available (you mayhave produced your own map from reconnaissance surveys).

� prismatic compass (in a protective case): essential, not only for making maps and determining survey routes, but also to help teams return to camp if they get lost.

� pencil/pen: propelling pencils, which need no sharpening, are mostconvenient, or pens with waterproof (India) ink. Ordinary ballpoint pens are NOT recommended for data recording: the ink is not waterproof, and your data sheet or notebook will be a mess if it gets wet.

� torches (preferably six-battery) and headlamp for night-time work(spare bulbs and batteries are essential).

� watch and/or stopwatch (should be easy to read in dim light conditions).

� field identification guides: these are discussed in more detailunder the ‘Methods’ section of each chapter. Avoid the use of large,cumbersome reference works (which are best consulted back inthe office/laboratory), and stick with lightweight, compact fieldguides. A species checklist for the area (if available) is advisable,or a preliminary list compiled from expected occurrences.

� binoculars: these are the most essential piece of equipment forsurveys of larger mammals, and especially birds. Binoculars arenormally labelled as 7x30 or 8x40, and so on. The first figure repre-sents the order of magnification, and the second the diameter ofthe objective lens measured in millimetres. The larger the secondfigure is, the greater the light-gathering potential of the lens. Forforest work, a wide field-of-view and plenty of light-gathering capac-ity is best. The best magnifications are 7x and 8x; higher magnifica-tions (10x) may allow you to identify birds in the treetops more eas-ily, but will be less effective for more close-up work. The objectivelens should be at least x40. A telescope (mounted on a light-weighttripod) is surprisingly useful for identifying treetop birds. Ideally,both binoculars and telescopes should be weather-proof; if they arenot, then carry strong plastic bags for protection against rain (zip-lock bags are useful if available).

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� photographic equipment: a good camera is often useful for takingphotographs of survey areas, different types of habitats, evidence of human activities, captured or surveyed specimens, etc. Equipment can range from inexpensive instamatic cameras that provide basic records of survey areas or details of animals and their signs, to expensive telephoto equipment for quality images that can be used in campaigns to raise awareness and as education materials. Different film speeds, an assortment of lenses,a flash (for photography in poor light conditions), and a protective bag are recommended. In addition, the increasing availability, resolution and affordability of digital cameras means that they are now a very valuable tool for specimen identification and for permanent recording of habitats trapped in, and so on. A quick digital image of each trap line (or specimen) is a cost-effective, or at least a valuable, addition to written descriptions of habitat (or specimens).

� optical (or laser) range finder (for estimating distances).� (optional): Global Positioning System (GPS) for recording the

start and end of transects, or positions of point counts.� a first-aid kit (see below).

There is, as they say, no substitute for experience, and if you have notconducted many surveys it is important to try to have in your team experiencedsurveyors to help you.

2.6 A note on market surveysand questionnaires/interviews

Although not discussed for each group, there are two additional surveymethods which have great relevance for surveying African forest vertebrates:market surveys and questionnaires/interviews.

Local markets can produce some interesting information about the localfauna, especially for general surveys. This is especially so for vertebrates inWest and Central Africa, particularly in light of the boom in the bushmeat trade.In many markets there are stalls selling dead mammal species such as smallantelope (particularly duikers), monkeys, chimpanzees and gorillas, pangolinsand rodents, especially canerats (or grasscutters, as they are known in WestAfrica). However, determining the origin of market carcasses is often very diffi-cult, especially for smoked meat that has been trucked a long distance andbeen through the hands of a number of intermediaries.

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At the local level, even more important are interviews with local peopleranging from local farmers, and particularly those that hunt, to forest, wildlife,national parks and other government officers. These people have considerableknowledge about animals in the area where they live and work, but care mustbe taken in verifying their verbal reports. For example, many villagers fail torecognise animals from pictures in guidebooks, and misunderstandings canarise through the misuse of local names, etc. Hunters, who tend to be mostknowledgeable, are often reticent on the whereabouts of their future bag. Onlyclear descriptions and explanations, ideally from independent sources, shouldbe recorded, and these should only be added to the dataset after further verifi-cation.

Having noted the limitations of market surveys and interviews, which canonly be overcome through several months of field work, much information onforest animals’ ecology, population status and levels of threat can be obtained.This has been done effectively for forest animals in: Sierra Leone (Davies &Richards, 1991); south-east Nigeria (Angelici et al., 1999); DemocraticRepublic of Congo (Dupain et al., 2000).

2.7 Health and safety Survey work involves many health and safety risks, including injury,

infection, and disease. Safety precautions during observational surveys are largely common

sense, and include wearing the correct clothing and using the right equipment,and, if possible, working in pairs rather than alone. When doing any kind ofwork off well-used trails, ensure that you have a GPS or compass, and a map,and that other members of the team know where you are working. Good surveymanagement dictates that a basic first-aid kit is carried along on field work atall times, that everyone knows where the first aid equipment is, and that every-one knows how to use it. Discuss possible problems with medical expertsbefore starting the expedition so that the first aid kit is correctly andappropriately equipped.

Working with large mammal species, like primates, ungulates and carni-vores, carries with it obvious risks. Be constantly on the alert and aware of yoursurroundings, being careful not to become so focused on a particular bird orreptile that you lose awareness of other, more dangerous wildlife.

Handling small mammals, herptiles and birds also carries the risk ofinfection from disease or ectoparasites. Protective gloves and a surgical/face-mask may be necessary depending on the type of work being done. Alwayswash your hands thoroughly after handling any animals.

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A wise precaution before undertaking any survey work is to get injectionsagainst tetanus and rabies. This may require more than one injection, so allowtime for the full course before the fieldwork begins. Similarly, courses of anti-malarial tablets often need to be started several days before departure (andshould be continued for several weeks after leaving the malaria area).

Additional notes on health and safety, where relevant, are provided in theindividual chapters.

2.8 ReferencesAngelici, F.M., Grimod, I. & Politano, E. (1999). Mammals of the Eastern Niger Delta (Rivers andBayelsa States, Nigeria): An environment affected by a gas-pipeline. Folia zool. 48(4): 249–264.

Davies, G. and Richards, P. (1991). The Rainforest in Mende Life. Unpubl report. Escor/ODA,London.

Dupain, J., van Krunkelsven, E., van Elsacker, L. & Verheyen, R.F. (2000). Current status of thebonobo (Pan paniscus) in the proposed Lomako Reserve (Democratic Republic of Congo). Biol.Cons. 94(3): 265–272.

Fauna & Flora International. (2000). Code of conduct for researchers. Oryx 35 (2): 99.

Mitani, J.C., Struhsaker, T.T. & Lwanga, J.S. (2000). Primate community dynamics in old growthforest over 23.5 years at Ngogo, Kibale national park, Uganda: implications for conservation andcensus methods. Int. J. Primatol. 21: 269–286.

Newmark, W.D. (1991). Tropical forest fragmentation and the local extinction of understorey birdsin the East Usambara Mountains, Tanzania. Conserv. Biol. 5: 67–78.

Noss, R.R. (1990). Indicators for monitoring biodiversity: a hierarchical approach. Conserv. Biol. 4:355–364.

Plumptre, A.J. (2000). Monitoring mammal populations with line transect techniques in Africanforests. J. Appl. Ecol. 37: 356–368.

Walsh, P.D. & White, L.J.T. (1999). What it will take to monitor forest elephant populations.Conserv. Biol. 13: 1194–1202.

White, L. & Edwards, A. (2000). Conservation Research in the African Rain Forests: a TechnicalHandbook. Wildlife Conservation Society, New York, USA.

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3. Amphibians and reptiles: the herptilesKim Howell

3.1 Biology

Herpetology is the study of amphibians and reptiles, and these twogroups will be collectively referred to as herptiles in this chapter.

Amphibians (Class Amphibia)The best known amphibians are the anurans, the frogs and toads, of

which there are about 161 species in East Africa, supplemented by about 10species of apodans or caecilians (legless forms) found in forests in Kenya andTanzania; there are about 600 anurans and 22 species of caecilians knownfrom the continent. Apodans live mostly in moist soil, and emerge only afterheavy rains, and, although the same can be said for many anurans, our discus-sion of survey methods focuses on frogs and toads, excluding the few specieswhich are entirely aquatic. Furthermore, the assessment of larval forms is onlybriefly addressed; this topic is covered in more detail by Heyer et al. (1994) intheir detailed review of amphibian survey methods.

Most frogs and toads are extremely seasonal in their reproductivebehaviour. In drier periods, many seem to simply disappear; they seek shelterwhere they will not be exposed to desiccating conditions, and are not seen orheard during the daytime or at night. However, during the rainy season(s)amphibians emerge and become much more active. They may still remain rela-tively hidden during the daytime, but at night male frogs and toads of manyspecies produce loud vocalisations that serve to advertise their presence inorder to attract females and also to defend their territories from other males.

twig snake

(Thelotornis kirtlandii)

Reptiles (Class Reptilia)It is mostly the snakes and lizards that occur in forests, though terrapins

may be associated with wetlands in forests, and tortoises are occasionallyfound at the forest edge. These come from the following groups of reptiles:lizards (including geckoes and chameleons); snakes; amphisbaenians (orworm-lizards); chelonians (marine turtles, freshwater terrapins, and terrestrialtortoises); and crocodiles. In sub-Saharan Africa, the approximate numbers ofspecies for these groups are as follows: chelonians (excluding sea turtles), 26;lizards, 680; amphisbaenians, 66; snakes, 466, and three species ofcrocodiles.

Much of our knowledge of reptile distribution in forests is still rather limit-ed, being restricted to preliminary species lists. For example, in Tanzania atleast four species of lizard and two snakes new to science have been foundwithin the past few years (Broadley, 1994, 1995a,b; Broadley & Wallach, 1996;Pasteur, 1995) and more surveys are needed. Reptiles are found from belowthe soil level to the tree canopy, so there are a variety of forms ranging fromthe fossorial to the arboreal.

3.2 Management issuesWorldwide, amphibians seem to be declining for poorly understood rea-

sons (Wyman, 1990). Recent research indicates that two cases of frog massextinctions in rain forests are a consequence of fungal pathogen attacks(Berger et al., 1998), and elsewhere tadpole deaths from fungal attack havebeen linked with climate change and ultra-violet radiation (Kiesecker et al.,2001). We do not have data on the impacts of pesticides, but given theincreasing use of agrochemicals, and the general increase in aquatic pollution,there is a need to monitor the levels of pollutants in the environment as well asin the tissues of amphibians.

As in other groups of vertebrates, there seems to be a basic splitbetween non-forest and forest species, and there is also a distinctly forest-dependent element that does not occur outside closed forest (e.g. Howell,1993). The forest-dependent amphibians are vulnerable to forest alterationand/or clearance, and are under threat in many parts of Africa. We do not yetunderstand the physiological reasons for the dependence on forest, but thenumber of hiding or retreat sites is a possible critical factor in limiting tropicalforest anuran populations (Stewart & Pough, 1983; Howell, 1993), especially ifforest quality is altered, and/or forest patch size decreases.

It is worth noting that this chapter focuses largely on amphibians whichare forest dwellers, and which make use of temporary pools for breeding, orwhich are independent of free water for reproduction (e.g. Nectophrynoides

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spp. toads, Arthroleptis spp. frogs, the bush squeakers, and some microhylidfrogs). However, recent studies have shown that even savannah species thatbreed in seasonal wetlands rely on forest as a dry season refuge.

Aside from local extinctions of forest-dependent amphibians and reptilesas a result of forest loss and degradation, the isolation of once continuous pop-ulations can be another problem. At present, no data exist as to the long-termeffect of such isolations. A corollary to this is that areas of degraded forest mayeffectively become a means by which non-forest dependent species caninvade; this already has occurred in many places along forest roads. In Africa,the paucity of information makes it difficult to develop predictive models for theabundance of amphibians and reptiles based upon capture data and measuresof habitat quality.

As many species of forest-dependent reptiles (and a few amphibians)are sought after by collectors for the live animal trade, there is a particularneed to be aware of this pressure, especially on populations in already isolatedforests, or near sites frequented by visitors. Commercial collecting, for exampleof chameleons, should be discouraged in such places. The larger reptileswould appear to be relatively long-lived, and intensive commercial collecting ina small area may have significant effects on populations.

Amphibians and reptiles form an important part of the forest ecosystem,where they are significant predators on invertebrates as well as smaller verte-brates, and they themselves are important food items for birds and mammals.This also applies to large snakes (whether venomous or not), which eat manyrodents, and can therefore also be beneficial to villagers.

A management issue peculiar to snakes is that because some of thelarger, more conspicuous species are venomous and potentially dangerous toman (see section 3.5), snakes in general are often regarded as harmful, andkilled. In fact, relatively few species of snakes are dangerous to man, and it isimportant for managers to be aware of this, and also to educate others that it isnot necessary to kill all snakes. This will undoubtedly encounter cultural resis-tance where snakes, and other herptiles, are part of local peoples’ beliefsystems.

3.3 MethodsGeneral

Our lack of knowledge about most forest herptiles means that currentsurveys deal largely with the building up of species lists, rather than indices ofabundance or population studies (e.g. Broadley & Howell, 1991; Drewes &Vindum, 1994). Efforts have been made, in West Africa (Barbault, 1975) and in

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eastern Africa (e.g. Western, 1974; Kreulen, 1979), to estimate populations ofreptiles, but these have usually been of large and/or conspicuous species inopen, drier habitats.

There are, therefore, few standard methods that have been used toquantify amphibian and reptile populations. Those that have been used inAfrica have dealt with forest, leaf-litter-dwelling anurans and reptiles inCameroon (Scott, 1982), or anurans in open areas such as small seasonalbreeding ponds (Bowker & Bowker, 1979). No satisfactory methods have yetbeen developed to sample the arboreal tree frogs, the fossorial apodans, orcanopy-dwelling reptiles that are the focus of this chapter. Chameleons, forexample, are hard to detect during the daytime and are best surveyed at night(e.g. Broadley & Blake, 1979; Jenkins et al., 1999), while snakes are verymobile and also difficult to detect. Studies of populations of anuran larval popu-lations also appear to be lacking in East Africa.

IdentificationA number of useful references and field guides are available for identify-

ing amphibians. Frost (1985) edited a world list of amphibian species thatserves as a basis for national and regional lists; in addition, African tree frogsare covered by Schiotz (1999). Other African national lists include: Stewart(1967), which provides a general introduction to some of the species found ineastern Africa; Rodel (2000), which covers many savannah species in WestAfrica; Fischer and Hinkel (1992), which describes Rwandan forms; Passmore& Carruthers (1995), covering South African frogs, many found in open habi-tats; Pitman (1974) which covers the snakes of Uganda, and Lambiris (1989),which gives useful general information on the biology of many species inZimbabwe, including drawings of the tadpoles. At least two of the newer guide-books feature CD-ROM recordings of frog vocalisations (Passmore &Carruthers, 1995; Rodel, 2000), which allow species identification without theneed for specimen collection.

Field guides currently available for reptiles are Branch (1998), which cov-ers southern Africa and includes many common woodland (but not forest)species found in eastern Africa; MacKay & MacKay (1985), which gives detailson how to identify venomous snakes in East Africa; and Broadley & Howell(1991), which provides a key and annotated list of species for Tanzania.Spawls et al. (2002) will provide coverage for East Africa, including Rwandaand Burundi. Older references include: Spawls (1978), which lists snakes ofKenya, and Schmidt & Noble’s (1919–1923) recently reprinted descriptions forWest Africa. Glaw & Vences (1994) should prove useful to anyone conductingsurveys of Madagascan herptiles.

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3.3.1 General surveysWhen visiting an area for the first time, either to begin building up a

species list, or to carry out a rapid assessment of sites for future studies, ageneral survey can be carried out to gather basic information.

General surveys provide at least a minimum of information on specieswhich may be present in an area. It is usually after a general survey has beenconducted and unusual and/or interesting species found that more detailedstudies are conducted. In most cases, a general survey will be done over ashort period of time using qualitative rather than quantitative methods of sam-pling and with little or no strict sample design. Nevertheless, general surveysare a useful way to involve local residents in participating in activities and win-ning their good will and confidence; they often have a detailed local knowledgeof particular species or habitats, and without their assistance a survey will usu-ally fail to detect even common species which may be present.

Equipment� cloth bags (various sizes – 80mm x 500mm to 140mm x 1000mm)

plastic bags for specimen collection� short handled rake or hoe for turning stones, logs, etc.� gardening gloves� snake tongs or grabbing stick (for picking up and handling snakes)� a shorter type of grabbing instrument (like artery forceps) for

grabbing small snakes, or controlling the heads of larger ones that have been grabbed or pinned down with a larger stick

� lizard noose (a loop of string held on a stick which permits you toslip it over the head of a lizard)

� catapult for collecting specimens from the canopy� weighing scales

Site selection and procedurei) It is necessary to take a number of different approaches during a gen-

eral survey in order to establish whether amphibians and/or reptiles are pre-sent. During the daytime, surveying under relatively dry conditions, you shouldsearch hiding places, such as inside rotten logs, under bark, in leaf-litter at thebase of trees (especially between tree buttresses), and in any tree cracks orholes. Old pit sawing sites in the forest, with the associated moist sawdust androtting stumps and planks, have also proved especially productive. For micro-hylid anurans, crevices in road cuts and banks of soil should also be searched.

ii) More and more emphasis has recently been placed on the need tosample not only adult amphibians, but also the larvae (e.g. frog and toadtadpoles). For many African species, these have not yet been described, and in

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many cases the adults may no longer be in the area, leaving only the tadpolesas evidence of the species’ presence. There is thus a need to sample tadpoles,catching them with simple nets (mosquito netting sewn onto a small wooden ormetal frame is fine for non-quantitative methods), seeking them in aquatic veg-etation and under rocks and logs in pools where they like to hide. The eggs ofamphibians can also be diagnostic of a species, and these should be collected.

iii) It is useful to raise the tadpoles, from eggs if possible, in order tomonitor their features as they develop, and eventually identify the species oncethe larvae have metamorphosed into adults. This involves keeping tadpoles injars; many are filter-feeders and will survive on the water from the collectingsite, as long as it is regularly changed. Each larval developmental stage shouldbe collected and stored in 10% formalin solution, with careful labelling. An alter-native is to collect from the site over a period of time that allows all stages ofdevelopment, from egg to adult, to be collected. However, either method is timeconsuming, and may not be feasible during short survey visits. A more detailedand quantitative approach to estimating tadpole densities is given by Heyer etal. (1994).

iv) Night-time surveys for amphibians, and perhaps some geckoes,involve listening for (and making tape recordings of) vocalisations, and visualsearching of suitable resting sites with headlamps and torches. Streams thatflow through forests can be sampled using both pit-fall traps, as well as audiotransects (as long as the background noise of rushing water does not block outthe frog vocalisations). Remember that while some frogs and geckoes live onthe forest floor, others are found at varying heights, at least up to 5m, on trees.

v) Reptiles can often be collected in similar situations to amphibians,namely under rocks, the bark of trees, and so on. They may also be seenbasking on and above the ground. Indeed, it can be helpful to place sheets ofmetal, wood and cardboard besides tracks and roads to attract reptiles. Night-time collecting is also required for some snakes, geckoes (none of the eastAfrican species give loud vocalisations), and chameleons; the latter are oftenvisible when asleep, clinging to vegetation at different levels above the ground.Be especially aware of the need to collect fossorial and burrowing forms, suchas blind snakes and legless lizards – these are seldom sampled and poorlyknown. It is important to realise that general surveys are likely to under-repre-sent the larger species, such as ridged or grass frogs (Ptychadena), and sometree frogs.

vi) Indirect methods may be employed to detect the presence of aspecies, such as through information from local inhabitants (indigenous/localknowledge) and by examining the faeces/scats from some predators. Theidentification of reptile bones in owl pellets, and prey remains of large raptors,especially crowned eagles (see Msuya, 1993), as well as reptile and amphibian

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remains in mammal faeces, may all provide information on the presence of aspecies (see Yalden, 1977). This is important in the case of apodans and leg-less lizards that are often not detected by conventional trapping but may beprey items of larger snakes.

vii) Information gathered during these general surveys could be used tostratify a large area into separate zones with characteristic differences (e.g.marshy; woodland; near rivers) that influence herptile distribution and abun-dance. Thereafter, longer surveys and studies may be carried out in each ofthe various zones so that a full picture of the herptiles in a forest region isobtained.

Recordingi) Record each individual animal and its species name (Form 3.2). If you

do not know its name, then call it ‘species a’, etc. ii) Take the standard measurements for each specimen along with any

geographical and habitat information. General data required is similar to thatcollected for small mammals (section 4.4), with some obvious differences. Inparticular, some additional notes and measurements should be recordedincluding snout length (in the case of reptiles), iris colour/shape, and any othernotes on anatomy, such as eyes (e.g. protruding) and feet.

iii) Detailed notes need to be made of the colouration of the animal, sup-ported, if possible, by colour or digital photographs (some people prefer to takethese after the animal has been anaesthetised). Colour is a key feature in theidentifications of amphibians, and once immersed in preservative the brightcolours often fade to brown or white.

iv) Collect and preserve voucher specimens (see section 3.4)

Advantages/limitationsThe general survey technique continues to yield important information in

East Africa, but is best used in conjunction with some of the following tech-niques such as pitfall traps and litter searching. Unfortunately, it does not pro-vide information concerning populations, and it is difficult to quantify the resultsobtained from this type of collecting survey, especially given seasonal andannual variation.

3.3.2 Drift fences and pitfall trapsThis is a method that has been employed recently for sampling small

mammals in forests, and has been shown to be especially effective in samplingleaf-litter frogs of the genus Arthroleptis, as well as Bufo toads and forest floorlizards.

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The basic principle behind this trapping method is that animals on theforest floor encounter a barrier termed a ‘drift fence’ which causes them to driftinto the trap. Rather than cross the fence, burrow under it, or break through it,they take the route of least resistance by moving either right or left and follow-ing the fence – which leads them to drop into a pitfall trap.

A variety of patterns of arrangement for the bucket pitfall traps havebeen used, with varying degrees of success (see Bury & Corn, 1987).Presented here is the simplest arrangement: a drift fence in a straight line,termed here a ‘pitfall line’ (Fig. 3.1), using 20-litre plastic buckets for the pitfalltraps and plastic sheeting for the drift fence.

Equipment� eleven plastic buckets (size: 20 litre), or any reasonable alternative

which is sufficiently wide to prevent animals jumping across, andsufficiently deep to prevent them jumping out (for example, largeempty tins). It is important to use containers that are readily avail-able. The buckets should have covers so that they can be closed inrainy weather or when they cannot be monitored.

� plastic sheeting (length: 55m). This may be transparent or coloured;if the latter, black is likely to be a better choice, since bright coloursmay influence the catchability of some species. The exact heightand thickness are not critical and may be determined by availability;plastic sheeting is often sold as a roll of open-ended tubing inapprox. 0.5m widths, so this can be cut and used as a single thick-ness. Locally available alternative material may be equally effective(e.g. polypropylene gunny sack material, etc.).

� wooden stakes to support the plastic sheeting.� staple gun and staples for attaching sheeting to supporting stakes

(alternatively, you can punch holes in the sheeting and tie it to thestakes, but this requires much more time).

Fig 3.1: Drift fence and pitfall trap

5m

pitfallbucket wooden

stake

plasticsheeting

� a hoe and pick suited to cutting through roots.� measuring tape or string of measured length.

Site selectionMoist or low ground is usually a good place to trap, especially at the

bases of valleys, but try to set pitfall lines in a variety of situations and habitatsfor comparison. Remember that altitude is an important variable in the distribu-tion of amphibians. For comparisons to be made, the same method should beused at each sample site.

Procedurei) Configuration of trap lines: each trap line is 55m long, with buckets

placed every 5m. Thus, with one bucket at the beginning and one at the end,the total number of buckets is 11. There is nothing sacred about using a line55m long, and you can always use a shorter line depending on local circum-stances, but it is best to try to standardise the length and set-up so that youcan compare catch rates between different sites.

ii) Each bucket is sunk in the ground so that the upper rim is equal to, orslightly below the ground-surface level. This is very important; apparently, fewanimals will climb a mound of soil at the edge of a bucket, whereas if thebucket is level with or slightly below the soil surface, they readily fall in.

iii) The plastic drift fence is erected so that the line is continuous fromthe first to the last bucket in each line. The fence should pass over the centreof each bucket. The best way to keep the plastic erect is to drive stakes intothe ground along the drift fence and then to staple the plastic sheeting to thestakes. A stake is needed on either side of each bucket, and then at least fourto support the area of plastic sheeting between consecutive buckets. The linedoes not have to be straight, and probably will have to curve in places in orderto avoid trees, large rocks, and other obstacles.

iv) It is important to clear away vegetation that gets in the way of theplastic drift fence. The plastic sheeting must rest flush with the ground; if vege-tation props the bottom open, animals will move underneath the fence. Oncethe fence is in place and properly stapled, it is time to mound up a little soil onboth sides of the fence (to further inhibit animals from pushing underneath).

v) It is good practice to number each separate pitfall line, and then, with-in each line, number each bucket. This is best done with flagging tape attachedto a nearby stick. Try to map the pitfall line exactly using a GPS (GlobalPositioning System) or use longitude and latitude coordinates to allow survey-ors to come back to the exact spot and repeat the sampling. You also maywish to establish permanent markers indicating the sites of your pitfall line.

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vi) Remove litter such as leaves and soil from buckets daily. Checkbuckets regularly for stones or branches that may have fallen in as these mayallow animals to climb out. To ensure rain water drains from buckets, puncturethe bottom of each, and the sides if necessary (this also reduces the attractive-ness of the buckets to local residents!).

vii) Important note: When checking pitfall lines in early morning and lateafternoon or at dusk, or any other stage when the light is deteriorating and visi-bility is poor, always use a torch when examining the contents of the pitfallbuckets. Scorpions, centipedes and venomous snakes may be in the bucket inaddition to the frog you are about to pick up. Look carefully before you putyour hand in the bucket!

viii) After you have finished your trapping regime and removed the pit-falls and drift fence, fill in the holes that were dug for the buckets. This ensuresthat no animals will accidentally be trapped and no larger animals will injurethemselves when walking in the area. This will also enable the site to recoverquickly, an important point if you wish to sample the same area at another time.

Recordingi) Detailed notes should be kept on local habitat, soil type, amount of leaf

litter, ground cover, etc. for each pitfall line (Form 3.2); those describing theexact surroundings of each bucket may also be taken.

ii) The number of animals captured per night in each bucket should becarefully recorded; these data can then be combined to calculate the trap suc-cess of each pitfall line. It is important to record from which bucket each animalcame, rather than recording just catch per line. This permits later analysis,which may indicate which features of the microhabitat are related to thecapture of particular species.

iii) Information on captured species should be recorded on the standardform (Form 3.1).

Data analysisi) Most general survey work involving pitfalls will simply record trap suc-

cess, i.e. how many captures per number of (bucket) trap nights. This may thenbe compared with similar trap success for other types of traps, such as break-back traps in the cases of small mammals.

ii) Trapping success of pitfall lines at different elevations, or in differenthabitats, may also be compared.

iii) If adequate data are kept over a long period of time, it may also bepossible to study microhabitat features by comparing trap success of buckets,for example, which are located near fallen logs and those which are not.

iv) Simple graphs can be plotted of cumulative number of species (CNS)and cumulative number of individuals (CNI) against cumulative number of trapnights. If the CNS curve flattens out by the end of the sampling period, with fewor no species added during the last nights of trapping, then sampling likely hasdetected most of the species which are detectable using that method.

Advantages/limitationsi) The advantages of this technique are that it is easily repeatable, can

easily be modified to suit local conditions, and can be used to sample mam-mals, amphibians and reptiles simultaneously. It is also one of the few tech-niques that can be used to sample apodans and burrowing reptiles thatoccasionally emerge on the forest floor.

ii) It can be used as a non-destructive technique, and permits the mark-recapture method of population assessment (see below). However, this tech-nique only samples members of the forest floor community, and so will notsample tree frogs, for example.

iii) Occasionally, animals such as bushpigs or small antelopes may wan-der through the drift fence, necessitating repairs. It is good policy to check yourpitfalls first thing in the morning, and then again in late afternoon. A quick checkan hour or two after sunset will also allow you to detect early arrivals, andthese can be removed so that they do not spend the night exposed in thebucket; in dry, cold forest, some amphibians may perish overnight from dehy-dration and/or exposure, thereby necessitating more frequent checks.

Fig 3.2: Drift net fence

3.3.3 Canopy walkway trapA method of setting traps on walkways in the canopy. It involves

constructing a runway of mosquito mesh into which is sewed a funnel-shapedbag – the funnel trap. The entire construction is then raised by means of ropeand pulleys into the canopy (see Vogt, 1987 for details and a photograph). Thismethod works on the principle that reptiles will make use of walkways to travelthrough the forest canopies.

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Equipment� plastic mosquito gauze (also called mosquito mesh or window

screen)� galvanised wire� metal cutting scissors or tin snips� pliers and wire-cutters� steel rods (diam: 5mm; length: 1m), two for each walkway� pulleys (x 4); several walkways can be tied at different heights to the

same rope and pulley assembly)� nylon or other non-rotting rope to fit pulleys

Site selectionThis technique requires a site where the walkway will be touching as

many trees and branches as possible, but will still permit the use of pulleys toraise and lower it.

Procedurei) The basic feature of this method is a walkway made of plastic mosquito

mesh (window screen) (Fig. 3.3). Simply use this material in its standard width(approx. 1m), and in 15-m lengths (or any other length you can convenientlyhandle in the field). Metal wire (galvanised if possible to prevent rusting) isthreaded along the entire length of the plastic window screen on both edges; alength of the same wire is also inserted crosswise at 1-m intervals. Thesecross-wires serve to give support to the walkway. A 1-m length of steel-rod(diam. 5mm) is tied at each end of the screening to ensure a flat entrance ontothe walkway.

ii) Two funnel traps (1m x 0.8m) are then constructed of 8mm x 8mmgalvanised wire mesh and are sewn onto the walkway using galvanised wire at5-m intervals. The mouths of the funnel traps are as wide as the walkway, sothat any animal that moves along it is directed into the trap. A guide line ofstring or rope is attached to both sides of each funnel trap; when the walkwayis raised to its desired height these can be pulled tight and tied to trees orrocks to prevent it from inverting during winds and rains.

iii) Ideally, walkways should be used at three different levels on the sameset of ropes and pulleys: 3m, 10m, and 15m. The pulley system allows regularchecking of the traps. This is accomplished by lowering both ends of the walk-way at the same time.

iv) The funnel traps should be checked regularly, ideally early morning,midday, and late afternoon. Depending on the trap success and the size ofanimals captured, it may be necessary to increase the depth of the funneltraps, especially if large snakes are encountered.

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RecordingInformation on captured species should be recorded on the standard

form (Form 3.1).

Advantages/limitationsAside from climbing into trees and capturing by hand, this would appear

to be the only effective method for sampling species which live in the canopy,or even just above ground level in the forest. However, it is labour-intensiveand requires much experience to perfect. Furthermore, care should be usedwhen setting and dismantling the trap; always have at least one and preferablytwo other people present in case of falls and related injuries.

3.3.4 Snake trappingFritts (1988) developed a simple trap for snakes made of mosquito mesh

wire. The trap is baited with bird droppings or feathers, and might be effectivefor arboreal species that feed on birds. Some snakes detect prey mainly byolfaction, whereas others respond to visual stimuli. For this reason, it would benecessary to experiment with different baits. This technique is aimed at assess-ing populations of a particular species rather than for general survey work (Fig.3.4). However, it has proved useful even without bait and it can be used as asimple funnel trap for both lizards and snakes, and seems to work best whenplaced along a natural barrier, such as a log, large rock, and other obstacles. Itmight also be possible to use it with a drift fence, in an area with hard or rockyground which would be unsuitable for pitfall traps.

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Fig 3.3: Forest canopy walkway trap

30

Site selectionUnless one is setting the traps in a particular grid or other arrangement,

traps should be set in spots which look likely to have sufficient cover to attractthe snake species which are to be trapped. For example, a trap set out in acompletely or relatively open area would probably be less successful than oneset along a natural barrier or hiding site, such as a fallen tree, a rock or a deadlog. Small mammal tracks and paths may also be used by snakes when hunt-ing prey, and these might also make good setting sites.

Procedure and RecordingInformation on captured species should be recorded on the standard

form (Form 3.1).

Advantages/limitations This technique is labour-intensive and extremely time consuming.

Fig 3.4: Construction of a snake trap

A B

C

Steps in construction of a snake trap

A) make funnel from screening and cut 2.5cm – 5cm opening in apexB) make cylinder by rolling over the screening and stapling ends;C) insert funnel into cylinder and attach two cylinders together with plastic

screening

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3.3.5 Capture, mark, recaptureWhen animals are captured (using one of the methods described above),

marked, and released, the population can be sampled again using the samemethods of original capture to estimate population size. The details of thismethod are discussed in Heyer et al. (1994), and summarised in the next chap-ter (section 4.3.5).

Individual marking of amphibians and reptiles has been done traditionallyby digital clipping: the number and position of digits clipped provides each ani-mal with a unique number with which it can be identified if recaptured. It isimportant to be especially careful in the use of methods involving mutilation,and these should not damage the animal such that it is rendered incapacitated.

Other workers have used tags and even simply tied thread or elasticbands around the waist of an amphibian to mark it (Muze, 1976), while forsnakes, particular ventral scales may be notched or clipped (Ferner, 1979). Theparticular method of marking and numbering is carefully recorded in a note-book, and the animal released (Ferner, 1979; Waichman, 1992).

Marking animals raises ethical issues, especially because much painand suffering may be inflicted upon individuals if great care is not taken, and ifappropriate methods are not used. Marking methods should therefore be dis-cussed with experienced surveyors before carrying out fieldwork.

3.3.6 Forest litter plotsIn this method, a measured area of 2m x 2m (or any convenient size) is

cleared of every bit of leaf-litter and the amphibians within the area identifiedand counted. A portable ‘fence’ of plastic or metal may be used to enclose thearea for ease in sampling. Scott (1982) used this method to sample leaf-litteranurans in Cameroon.

Equipment� portable plastic or metal fence to help enclose the area to be

searched (made of corrugated sheeting or other material such as plastic sheeting used in drift fences (see above), c. 15cm high by1m long, or varying lengths)

� short-handled rake and/or hoe� cloth/plastic bags in which to hold sampled animals� spring balances (50g, 100g, 500g, etc.)� tape measure (30m)� preservation material for voucher specimens

Site selectionSelect sites to be sampled; these will depend on your reasons for sam-

pling. For a general survey, try several different habitat types within the forest,such as dry, hilly; moist, valley; disturbed versus undisturbed, and so on. It isimportant to adequately describe, using standard methods, the habitat andmicrohabitat of the area searched. If you are attempting to compare differentsites or habitats, or to assess altitudinal differences or differences betweendisturbed and undisturbed areas, then you may wish to randomise your sampleareas within a particular habitat type.

Procedurei) Measure out the area to be searched and enclose with a suitable

‘fence’. Carefully search through the leaf-litter, using a small hoe or short-han-dled rake to move the leaf-litter away from a patch of ground in case snakes,scorpions, etc. are also present. Collect animals by hand and place in clothbags.

ii) It is best to sample as many sites as possible; it is likely at least 20sites with animals present will be needed to meet the requirements of statisticaltests.

RecordingInformation on captured species should be recorded on the standard

form (Form 3.1).

Data analysisThis method permits calculation of precise density figures. By measuring

mass it is also possible to calculate biomass per unit area. Depending on howthe sampling was done, it may be possible to compare counts made in differenthabitats, at different altitudes, etc. Measures of standard error must then becalculated to assess the reliability of population estimates.

Advantages/limitationsThe method samples only small forest leaf-litter anurans; it is labour-

intensive and will usually require more than one searcher. In some forests,herptile densities may be so low as to make assessment by this technique diffi-cult. Microhabitat requirements and/or seasonality factors may result in situa-tions arising in which an area sampled may yield no herptiles, while a plotimmediately near that one might have high numbers. Thus, it is generallyunsuitable for a species with extremely narrow microhabitat requirements.

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3.3.7 Time-constrained searchesIn a time-constrained search, the observer attempts to exert a continu-

ous sampling effort over a particular area or transect for a limited period oftime. For most reptiles and amphibians, this method is difficult to use becausesome are extremely cryptic when not calling, and many hide under vegetation.Nevertheless, this technique may prove useful when animals are conspicuous,such as at breeding aggregations.

Equipment� stopwatch (or watch which indicates seconds)� plastic/cloth bags� collecting and preserving material

Site selectionUnless you are using a randomised approach, then in practice the

observer picks what would be regarded as a ‘typical’ situation, site or habitat. Ifyou are sampling an entire study site, then there is a need to identify all of themajor habitat types present. These need to be characterised using standardmethods of habitat and vegetation description.

Procedurei) Determine an area that is going to be surveyed, and then set a block

of time (5–25 minutes), during which full concentration can be maintained forsearching (in a standardised way). Take rests between search blocks (5 min-utes or so). The observer should move slowly along survey transects and otherpaths, making every effort to look all around, up and down.

ii) Heyer et al. (1994) describe a procedure for time-constrained searchesof amphibians, and note that variables such as time spent on the survey, andusing each collecting technique, number and experience of fieldworkers, topog-raphy and size (area) of site to be surveyed, local weather and climate, sea-son, date and time of day all need to be considered and controlled for.

iii) For amphibians, the most efficient time to survey is usually at night. Itis useful, however, both in the interests of biology (it is possible to collect eggs,larvae and adults in the daytime) and safety (it is easier and safer to move overoften difficult topography at night if you have seen it during the daylight hours)to make a preliminary survey of the area to be sampled during the day.

Recordingi) The observer carefully records the time spent searching a particular

site; if more than one person is searching, it is important to record the numberof searchers.

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34

ii) General information on the site should also be recorded, such asheavy herb cover, any fallen logs present, etc. to give a picture of the situationand to allow for possible later comparisons. A detailed habitat description of thesite is especially important.

iii) The number and species of animals encountered and/or captured isrecorded. Information on captured species should be recorded on the standardform (Form 3.1).

iv) It is also important to note (in a notebook or on Form 3.2) the weatherconditions, phase of moon (if field work is done at night), habitat, number offieldworkers, time spent searching, etc.

v) For both reptiles and amphibians, it is often necessary to search byturning over fallen logs, searching under bark, etc. The time spent using thesedifferent methods by each worker is carefully recorded.

Data analysisThe time spent searching is multiplied by the number of searchers to

give the ‘total hours spent searching’; this, in turn, is related to the sightings perhour. Time species counts may be used either to detect number of species orthe number of animals collected.

Advantages/limitationsThis technique is probably best suited to sampling animals which are

fairly visible from a distance, and therefore not applicable for many forest situa-tions except when amphibians have congregated for breeding. It may be usefulfor reptiles that are ‘sit and wait’ predators, such as geckoes, which oftenoccupy relatively conspicuous sites at night; it may also be applicable for night-time counts of chameleons.

3.3.8 Transect countsSuch counts might be used for conspicuous species, such as skinks,

which scuttle away from a path as an observer walks it. The transect methodsare discussed in Chapters 5 and 6. Jenkins et al. (1999) describe the use of amodified line transect count method for surveying chameleons at night inMadagascar.

3.3.9 Territory mappingThis technique can be used for lacertid lizards and for agamas, which

are markedly territorial. The locations of individual territorial males are deter-mined and then plotted on a map of the study site. However, it is very time-consuming and labour-intensive, and probably would be used only if you wereconcerned with a particular species or population.

3.3.10 Sound recording surveysParker (1991) has argued convincingly for the use of tape recordings in

avifaunal surveys, and his arguments also hold for surveys of amphibians.Tape recordings have been made of many frog vocalisations (Schiotz, 1999;Passmore & Carruthers, 1995; Rodel, 2000); Heyer et al. (1994) suggest proto-cols for recording of amphibian calls. This technique is not applicable to rep-tiles, because none of the African species vocalise with sufficient volume andregularity to be useful for such an approach. For additional information onusing sound recording surveys see sections 6.3.2.c and 7.3.9.

Equipment� high-quality portable tape recorder or mini-disc player� microphone and batteries� blank tapes or mini-discs� recorded tapes/CDs of frog sounds� plastic bag or similar for protecting equipment against moisture

Site selectionTape recording may be conducted in the form of a general survey, or

sampling might be randomised to meet a particular experimental set up.Remember that some anurans may be photophobic and thus may not call asmuch or with the same intensity on a night with a bright, large moon as on adark, moonless night.

Procedure and Recordingi) Two approaches are possible. One is to record individuals as heard,

and try to approach and capture these animals for identification; preferably aspecimen with its field number noted on the recording of its call. A secondapproach is to place the tape recorder at a particular site and record 5–10 min-utes of the general calling sounds of amphibians. When recording specieswhich are sensitive to the approach of an observer/recorder, a useful approachis to have a long microphone cable; the microphone is left near the animalwhich has been vocalising, and the observer/recorder simply retreats to acertain distance, and records using the long microphone cable.

ii) Give full habitat data, time of day, exact locality, name of surveyor, airand water temperature, and other relevant details. Effectively, the tape is aspecimen, so it too must have as much precise data on it as possible. Longperiods of natural anuran sounds are valuable and lacking in most soundlibraries.

35

iii) A sample recording data sheet based on that of the Macauley Libraryof Natural Sounds at Cornell University is provided (Form 3.3).

Data analysisi) By collecting detailed data on individual as well as community vocali-

sations, a record is built up which will enable most species to be identified byvoice alone. Well-documented recordings also serve as valid records of aspecies.

ii) Copies of these recordings should be deposited in a professionally-maintained sound collection where they will be available for researchers. Suchinstitutions include national museums, the British Library of Wildlife Sounds, orthe Macauley Library of Natural Sounds at Cornell University, Ithaca, New York,USA.

Advantages/limitationsBecause sound is so important in anuran biology, this technique adds

considerably to our knowledge of the species concerned. The human ear isvery fallible; the tape recorder, however, records all sounds (within the limita-tions of its microphone and the tape response), thus creating a permanentrecord that can be assessed by others at a later date. It also permits identifica-tion of species that were not heard or seen by the recorder or other collectors,and detailed sonographic study is possible in the laboratory.

3.4 Specimen handlingGiven our rudimentary understanding about forest amphibians and rep-

tiles, specimens are needed to allow accurate identification by experts, and forfuture reference in the event of taxonomic revisions. Specimens that are col-lected, therefore, need to be preserved in an appropriate fashion (Knudsen,1966; Broadley, 1973; and Heyer et al., 1994, provide detailed instructions),and lodged in a suitable institution, museum or collection (see section 4.4).

The collecting of voucher specimens, or larger series of specimenswhere necessary, also permits other data, such as reproductive condition, to beassessed, and one can also obtain information important to population biology(such as number of eggs per female). Careful labelling of specimens, withcross-reference to field notes and photographs, is essential.

In addition to the whole specimen, many recommend that tissues of ani-mals routinely be taken and fixed separately so that DNA may be analysedlater. Similarly, it is extremely useful to collect tissues fixed in such a way thatthese may be used later for analysis of pesticides, metals, and other pollutants,as has been done to assess insecticide spraying in Zimbabwe (Lambert, 1993).

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3.5 Health and safetyBoth amphibians and reptiles may harbour ectoparasites and endopara-

sites, and also may be infected by fungi and bacteria. While usually these havebeen of little concern to those working with them, recently in some countriesthere has been concern expressed that freshwater chelonians sold as petsmay carry the Salmonella bacterium and cause disease. It is thereforeadvisable to take normal precautions when handling live animals as well asdead specimens, such as using gloves and/or carefully washing hands withsoap and disinfectant.

All amphibians have a glandular skin and some of the secretions aretoxic and if ingested, potentially fatal. Most toads (family Bufonidae), for exam-ple, have specialised glandular areas on the skin, the secretions of which con-tain powerful toxins. Other anurans, such as members of the genusPhrynomantis (formerly Phrynomerus) also secrete extremely irritating sub-stances from their skin glands. Although in both the toads and other frogsthese substances are not usually a problem for those handling them, if theworker has a cut or abraded area of the skin, irritation will result. Similarly, ifthe secretion is transferred to the eye, nose or mouth, severe pain and irritationmay result (Howell, 1978). Simply rinsing with water or other diluting liquids isthe best first aid.

As ably described by Cansdale (1962) in his book on West Africansnakes, and contrary to popular belief, very few people get bitten by snakes.Those that do seldom suffer severe consequences – it is more likely that some-one will be killed in a bus, or on a bicycle, than by a snake bite.

The venom of only a relatively few species is potentially fatal to humans.Despite the low risks, however, it is still important to take precautions to avoidbeing bitten by snakes, since surveying them does greatly increase contact.Sensible, strong field boots (canvas, leather or rubber) are important, and canbe supplemented with thick socks and denim trousers for the areas betweenankle and knee (where most snakebites occur). Safety gloves (e.g. gardeninggloves) as well as a snake stick are important when catching and handling. Inthe case of spitting cobras, which spray their venom at the eyes, safety gog-gles should be worn. All these precautions will reduce the chances of beingbitten by snakes.

In the unlikely event of a snake strike, every effort should be made, with-out risking further injury, to capture the snake (dead or alive) to show to first-aiders and medical staff. Snakes should be handled with extreme caution andreaders are strongly advised to learn to recognise the local venomous formsand to avoid handling them. Details of venomous snakes and snakebite treat-ment can be found in Spawls & Branch (1995).

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3.6 ConclusionsOur knowledge of amphibian and reptile biology and population cycles in

African forests is so rudimentary that substantially more survey work is neededbefore forest management actions can be taken to reduce the risks of herptilelosses.

General surveys and pitfall traps are probably the first survey methods touse at any site, supplemented with other methods outlined above where time,resources, and interest allows. Until more specialists are trained, and morefunding is available for detailed studies on populations, biologists will continueto carry out general surveys that indicate presence of amphibians and reptiles,rather than the much-needed detailed population surveys and studies. Specieslists are useful, especially those which are annotated and provide informationon the conservation status of the fauna of an area. It is important for forestmanagers to recognise when they have herpetofaunal assemblages of highdiversity and/or endemic, rare or endangered species of amphibians andreptiles in their area. They can then encourage individuals as well as organisa-tions with specialised training and experience to address the issues of amphib-ian and reptile populations in more detail than is currently the case.

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39

3.7 ReferencesBarbault, R. (1975). Les peuplements de lézards des savanes de Lamto (Côte d’Ivoire). Annal.Univ. Abidjan. Ser. B. Ecol. 8: 147–221.

Bennett, D. (1999). Reptiles and Amphibians: Expedition Field Techniques. Royal GeographicalSociety, London, UK.

Berger, L., Speare, R., Daszak, P., Greene, D.E., Cunningham, A.A., Goggin, C.R., Slocombe, R.,Raga, M.A., Hyatt, A.D., MacDonald, K.R., Hinas, H.B., Lip, K.R., Marantelli, G. & Parkes, H.(1998). Chytriomycosis causes amphibian mortalities associated with population declines in therainforests of Australia and Central America. Proc. Natl Acad. Sci. USA 95: 9031 – 9036.

Bowker, R.G. & Bowker, M.H. (1979). Abundance and distribution of anurans in a Kenyan pond.Copeia 1979: 278–285.

Branch, B. (1998). Field Guide to the Snakes and Other Reptiles of Southern Africa. 3rd edn.Struik, Cape Town, South Africa.

Broadley, D.G. (1973). Reptiles and Amphibians: Instructions for the Collection and Preservation.Trustees of the National Museums and Monuments of Rhodesia. 5pp.

Broadley, D.G. (1994). A review of Lygosoma Hardwicke and Gray 1827 (Reptilia: Scincidae) onthe East African coast, with the description of a new species. Trop. Zool. 7: 217–222.

Broadley, D.G. (1995a). A new species of Scolecoseps (Reptilia: Scincidae) from southeasternTanzania. Amphibia-Reptilia 16: 241–244.

Broadley, D.G. (1995b). A new species of Prosymna Gray (Serpentes: Colubridae) from CoastalForest in northeastern Tanzania. Arnoldia Zimb. 10(4): 29–32.

Broadley, D.G. & Blake, D.K. (1979). A field study of Rhampholeon marshall marshalli on VumbaMountain, Rhodesia (Sauria: Chamaeleonidae). Arnoldia Rhod. 8(34): 1–6.

Broadley, D.G. & Howell, K.M. (1991). A checklist of the reptiles of Tanzania, with synoptic keys.Syntarsus 1: 1–70.

Broadley, D.G. & Wallach, V. (1996). Remarkable new worm snake (Serpentes: Leptotyphlopidae)from the East African Coast. Copeia 1996: 162–166.

Bury, R.B. & Corn, P.S. (1987). Evaluation of pitfall trapping in north-western forest: trap arrays withdrift fences. J. Wildl.mgmt 5: 112–119.

Cansdale, G.S. (1962). West African Snakes. Longmans, London.

Drewes, R.C. & Vindum, J. (1994). Amphibians of the Impenetrable Forest, south-west Uganda. J.Afr. Zool. 108: 55–70.

Ferner, J.W. (1979). A Review of Marking Techniques for Amphibians and Reptiles. Society for theStudy of Amphibians and Reptiles Herpetological Circular No.9.

Fischer, E. & Hinkel, H. (1992). La Nature et l’Environment du Rwanda. Rheinmain Druck, Mainz,Germany.

Fritts, T.H. (1988). Instructions for making screen-wire snake traps. In: The Brown Tree Snake,Boiga irregularis, a Threat to Pacific Islands, pp. 28–30. US Fish Wildl. Serv., Biol Rep. 88 (31),36 pp.

Frost, D.R. (Ed.) (1985). Amphibian Species of the World. Allen Press & Association of SystematicsCollections, Lawrence, Kansas, USA.

Glaw, F. & Vences, M. (1994). A Field Guide to the Amphibians and Reptiles of Madagascar. 2ndedn. Moos Druck, Leverkusen, Germany.

Heyer, R.W., Donneley, M.A., McDiarmid, R.W., Hayek, L-A.C. & Foster, M.S. (1994). Measuringand Monitoring Biological Diversity. Standard methods for Amphibians. Smithsonian InstitutionPress, Washington, USA.

Howell, K.M. (1978). Ocular envenomation by a toad in the Bufo regularis species group; effectsand first aid. EANHS Bull. July/Aug: 82–84.

Howell, K.M. (1993). Herpetofauna of the eastern African forests. Chapter 9. In: Biogeography andEcology of the Rain Forests of Eastern Africa, pp. 173–210. (Eds. J.C. Lovett & S.K. Wasser).Cambridge University Press, Cambridge, UK.

Jenkins, R.K.B., Brady, L.D., Huston, K., Kauffmann, J.L.D., Rabearivony, J., Raveloson, G. &Rowcliffe, J.M. (1999). The population status of chameleons in Ranomafana National Park,Madagascar, and recommendations for future monitoring. Oryx 33(1): 38–46.

Kiesecker, M., Blaustein, A.R., Belden, L.K. (2001). Complex causes of amphibian populationdeclines. Nature 410: 681–683.

Knudsen, J.W. (1966). Biological Techniques. Harper & Row, New York, USA.

Kreulen, D. (1979). Factors affecting reptile biomass in African grasslands. Am. Nat. 114: 157–165.

Lambert, M.R. (1993). Effects of DDT ground-spraying against tsetse flies on lizards in NWZimbabwe. Environm. Poll. 82: 231–237.

Lambiris, A.J.L. (1989). The Frogs of Zimbabwe. Monografie X, Museo Regionale di ScienzeNaturali, Torino.

Larsen, D.P. (1993). The Reptiles of Korup National Park, Cameroon. Herp. Nat. Hist. 1(2): 27–90.

MacKay, A. & MacKay, J. (1985). Poisonous Snakes of Eastern Africa and the Treatment of theirBites. Published by the authors, Nairobi, Kenya.

Msuya, C.A. (1993). Feeding habits of crowned eagles Stephaonaetus coronatus in KiwengomaForest Reserve, Matumbi Hills, Tanzania. Proc. VIII Pan-Afr. Orn. Congr. 118–120.

Muze, E.S. (1976). Studies on the sex ratio and polymorphism in Hyperolius puncticulatus(Rhacophoridae) at Amani, Tanzania. MSc thesis, University of Dar es Salaam, Tanzania.

O’Shea, M. (1992). Reptiles and Amphibians: Expedition Field Techniques. Royal GeographicalSociety, London, UK.

Parker, T.A. III. (1991). On the use of tape recorders in avifaunal surveys. Auk 108: 443–444.

Passmore, N. & Carruthers, V. (1995). South African Frogs: A Complete Guide. Revised edition.Southern Book Publishers and Witswatersrand University Press, Johannesburg, South Africa.

Pasteur, G. (1995). Biodiversité et reptiles: diagnoses de sept nouvelles espèces fossils etactuelles du genre de lizards Lygodactylus (Sauria, Gekkonidae). Dumerilia 2: 1–21.

Pitman, C.R.S. (1974). A Guide to the Snakes of Uganda. Revised edn. Wheldon and Wesley. 290pp.

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Rodel, M.O. (2000). Herpetofauna of West Africa, Vol.1: Amphibians of the West African Savanna.332pp, including CD.

Schiotz, A. (1999). Tree Frogs of Africa. Edition Chimaira, Frankfurt am Main, Germany.

Scott, N.J. Jr. (1982). The herpetofauna of forest litter plots from Cameroon, Africa. In:Herpetological Communities. (Ed. N.J. Scott Jr.). U.S. Dept. Int. Fish Wild Ser. Wild. Res. Rept. No.13: 145–150.

Spawls, S. (1978). A checklist of the snakes of Kenya. J. E. Afr. Nat. Hist. Soc and Nat.Mus. 3 (67):1–18.

Spawls, S. & Branch, B. (1995). The Dangerous Snakes of Africa. Blandford, Cassell Group,London.

Spawls, S., Howell, K.M., Drewes, R.C. & Ashe, J. (2002). A Field Guide to the Reptiles of EastAfrica. Academic Press, London.

Stewart, M. (1967). Amphibians of Malawi. State University of New York Press, Albany, USA.

Stewart, M. & Pough, F.H. (1983). Population density of tropical forest frogs: relation to retreatsites. Science 221: 570–572.

Vogt, R.C. (1987). Techniques. You can set drift fences in the canopy! SSAR Herp. Rev. 18: 13–14.

Waichman, A.V. (1992). An alphanumeric code for toe clipping amphibians and reptiles. Herpetol.Rev. 23: 1992.

Western, D. (1974). The distribution, density and biomass density of lizards in a semi-arid environ-ment of northern Kenya. E. Afr. Wildl. J. 12: 49–62.

Wyman, R.L. (1990). What’s happening to the amphibians? Conserv. Biol. 4: 350–352.

Yalden, D.W. (1977). The Identification of Remains in Owl Pellets. Occasional Publication of theMammal Society. Reading, UK. 8pp.

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Form 3.1: Herptile Catch Records (instructions see p52)

Surveyor: Field sheet ref: Date:(total observers): (dd/mm/yy)

Address:

Survey site: Altitude: Aspect:

Latitude: Longitude: UTM (if available):

Vegetation: Human disturbance:

Soil type: Leaf–litter/ground cover:

Season: Weather: Lunar phase: Temperature:

Other:

Trap line Microhabitat Water Topography Species and Other& no. association specimen

sheet ref.

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Form 3.2: Specimen Records: herptiles

Specimen sheet ref: Field sheet ref:

Collector: Date: Time:(dd/mm/yy)

Address:

Collecting site: Altitude:

Latitude: Longitude: Slope:

Additional notes:

Species: Field no.: Sex (if known): Age:

Pregnant: Eggs: Breeding condition:

Colour/markings: Wounds:

Ectoparasites: Endoparasites:

Measurements:

HB TL TV Snout-vent Other Wmm mm mm mm mm g

Material Preserved:Skin Skull Skeleton Stomach Faeces Blood Liver Kidneys

Stomach contents:Component: Percentage:

Remarks/Other

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Form 3.3: Sound Recording Form

Species, Sound or Subject:

Recordist(s) and Address:

Date: Time: Weather:

Place: Latitude: Longitude:

Species/id

No. of individuals

Sex/Age

Breeding status

Sound Category

Response to playback

Notes:

For calls www.birds.cornell.edu www.bl.uk/collections/sound-archive/nsa.htmlContacts:Curator CuratorLibrary of Natural sounds NSA Wildlife SectionCorne Laboratory of Ornithology The British Library159 Sapsucker Wood road National Sound ArchiveIthaca, New York 14850, USA 96 Euston Road

London NW1 2DB, UK

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Glyn Davies and Kim Howell

4.1 BiologySmall mammals are a disparate collection of flying and non-flying

species that have been grouped together because of their relatively small size,despite obvious anatomical and ecological differences. In this chapter, weconsider three groups: rodents, bats, and insectivores (including elephant-shrews). All groups are elusive and difficult to survey because, in order to avoidpredators, they have evolved dull colouration, secretive behaviour and, in manycases, nocturnal habits. These characteristics, along with their small size,make field identification difficult – a problem exacerbated by the very highdiversity of African small mammal species (for example, there are about 190bats and some 380 rodents in Africa). These problems are no less acute forinsectivorous small mammals – there are about 165 African mainland species(many of them in the genus Crocidura alone). Mammal lists of the world(Corbet & Hill, 1991; Wilson & Reeder, 1993; Nowak, 1999), and regionalchecklists, may help to give a rough idea of the species present in an area, butonly surveys and collecting carried out over different seasons will permit amore accurate assessment of the species present in a given forest.

golden-rumped elephant shrew

(Rhyncocyon chrysopygus)

4. Small mammals:bats, rodents and insectivores

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Bats (Order Chiroptera) Bats are divided into two sub-orders: the fruit bats (Megachiroptera),

sometimes termed ‘megabats’, which use their large eyes and relatively longnoses to locate fruit and nectar/pollen food sources, and do not use high-frequency echolocation for navigation; and the insect-eating bats(Microchiroptera), or microbats, which make use of echolocation and hearing tofind insects and small fruit foods, as well as nectar and pollen. Species fromboth groups roost in the daytime, sometimes in large congregations, and aremost active soon after sunset, unless it is raining. Some are active during theday as well as at night, and during the night different species may show activitypeaks at different times.

Rodents (Order Rodentia) The rodents are usually divided into two sub-orders: the Sciurognathi,

which includes the squirrels, rats, and mice; and the Hystricognathi, represent-ed in Africa by the porcupines, mole-rats, cane-rats and dassie-rat. Somemembers of this diverse order are large (e.g. cane rat: 7+ kg; crested porcu-pine: 15+ kg) and all have powerful front teeth for gnawing. The mice and ratsmostly live in holes and forage for fruits, seeds, arthropods, etc. on the forestfloor, or under/along fallen logs. Most rats and mice are terrestrial, and mostsquirrels are arboreal – however, there are some rare exceptions to this rule:dormice and climbing-mice climb quite extensively in under-storey trees, whilesome large squirrel species are ground-dwelling.

Insectivores (Orders Insectivora and Macroscelidea)The insectivores belong to two mammalian orders: Insectivora, which

includes such diverse groups as the shrews, otter-shrews and hedgehogs, andthe Macroscelidea – the distinctive elephant-shrews (although there have beenrecent taxonomic revisions). The shrews are distinguished from rodents bytheir protruding snout, usually tiny eyes and elongated lower incisors. Most for-age in leaf-litter for live arthropods and other invertebrates.

An important characteristic of small mammals is that many have thereproductive ability to undergo large population increases during favourableperiods, and suffer substantial losses at other times. For species that showthese boom-and-bust cycles, estimates of population sizes are difficult toextrapolate from year to year. There are also considerable differences betweendifferent seasons, so surveys need to take careful account of this potentialbias; comparing dry season and wet season results will give a poor under-standing of population differences between forests. There may also be differ-ences in behaviour depending on weather conditions (e.g. mice shelteringduring rainstorms) and lunar phases (e.g. dark nights affecting fruit bat activity),so these factors should be recorded during surveys.

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4.2 Management issuesSmall mammals, especially the more abundant species, are important

components of forest ecosystems. All small species are preyed upon, andtherefore support populations of many groups of carnivorous and omnivorousmammals, birds and reptiles. Rodents that are not eaten are responsible forthe destruction of many plants’ seeds, but they can also play a key role in seeddispersal; for example, when squirrels cache (hide) seeds in stores that theyfail to relocate before the seeds have germinated. Bats also play a very impor-tant ecological role in the forest, through pollination of flowers and dispersal ofseeds from fleshy fruits.

Small mammals may also be good indicator species of habitat change,and some are pioneer species. Recent studies in southern Africa of smallmammals colonising disturbed coastal sand dunes have indicated the useful-ness of rodents and other small mammals, as indicators (for example in regen-rating coastal dune forests: Ferreira & van Aarde, 1997, and in central Africanforests along logging roads: Malcolm & Ray, 2000).

In their relationships with humans, there are a number of rodent speciesthat do considerable damage to crops and stored grains, and fruit bats that dosubstantial damage to soft fruits. As a result they are killed, often by trappingrather than shooting, to reduce crop losses. An important by-product of thesepest control operations is bush-meat – including polythene-wrapped fruit batsfor sale in supermarkets (e.g. Mickleburgh et al., 1992) and road-side carcass-es of cane rats (grass-cutters). Many other species have a neutral impact onagriculture, and some are beneficial in pollinating fruit and vegetable crops.

Recent conservation reviews indicate that rodents (Lidicker, 1989), bats(Mickleburgh et al., 1992; Hutson et al., 2001) and insectivores (Nicoll &Rathbun, 1990) are all declining in Africa. In the case of fruit bats, disturbanceor destruction of roosting sites, over-exploitation of useful species and conflictswith fruit-growers have been cited as the main causes of declines (Mickleburghet al., 1992). Schlitter (1989) listed some 67 species of African rodents (repre-sentative of eight families) as being of special conservation concern, whileNicoll & Rathbun (1990) listed 58 species of insectivores, including six of the15 elephant-shrew species, which need special conservation attention. For allthree groups, the most consistent cause of declines is modification, fragmenta-tion and loss of habitats, especially forest environments (see the 2000 IUCNRed List of Threatened Species (Hilton-Taylor, 2000) www.redlist.org, for recentinformation).

Another consistent comment in conservation reviews is that very little isknown about these groups, either in terms of where they are found, or theirecology and population biology (most work having been done in temperate

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zones). In this chapter, therefore, a summary of basic survey principles isgiven, along with an overview of the wide range of methods that have beendeveloped, many of which need to be adapted for particular species, orparticular forests.

4.3 Methods

GeneralThe methods used vary according to the particular group; obviously, bats

must be surveyed using techniques which differ from those used for rodents.Yet the general approach is similar and many of the factors to consider aresimilar or the same. A first principle is to obtain the maximum amount ofinformation about an individual detected or captured. This may be a relativelystraightforward procedure when dealing with a specimen, but obtaining infor-mation on flying bats or rodents glimpsed only briefly is challenging to say theleast.

IdentificationAs mentioned earlier, many small mammal species can be very difficult

to identify, and sometimes it is only possible to identify specimens to the levelof genus. There are few field guides available to aid in the identification ofAfrican small mammals, although Kingdon (1997) is an exception; however,even this guide is limited in its discussion and representation of the smallermammal species. Regional works, such as Rosevear (1965, 1969), Happold(1987) and Kingdon (1974), may be useful for identification, but they are allhefty tomes and cannot be carried into the field. In most cases, identificationwill need to rely on the use of identification keys, many of which are only avail-able for individual families or genera and are not widely available.

Furthermore, the identification of small mammals, especially shrews androdents, to species level, usually requires a detailed examination of the skulland teeth. This effectively means that some animals must be sacrificed toserve as voucher specimens, and sent to museums outside of the region forexamination and study by specialists. Thus, the preservation of voucher speci-mens (at least 10 individuals of each sex per species) is a necessary and vitalpart of any small mammal study.

However, a new effort aimed at students of mammals in Tanzania is justbearing fruit. W. T. Stanley of the Field Museum of Natural History, Chicago,Illinois, U.S.A., with financial support from the MacArthur Foundation, hascreated a key to African mammals using either skulls or skins. While still in apreliminary stage, this can be accessed at: www.devdirection.com/tanzania/

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4.3.1 General surveysGeneral surveys can be used to start plotting the distribution of species,

in different habitats and at different altitudes, and to select sites for moredetailed investigation. All the information gathered during general surveys canbe mapped to show species’ distributions (section 6.3.1).

For bats, dusk-time walks near forest streams, potential roosting sites(e.g. caves) and fruiting/flowering trees provide an indication of bat numbers.Checking caves, hollow trees and fallen logs may also be rewarding, even inthe daytime. For rodents and insectivores, searching under fallen logs for runs,where tiny feet have left a distinct path, as well as for signs of discarded foodremains or faecal pellets, may help identify sites that could be sampled laterwith traps. In the case of elephant-shrews, spherical nests of grassy material inthe leaf-litter, as well as runs, are indicative of their presence.

Other indirect signs of small mammal presence include their teeth, skulland other skeletal remains in owl pellets (regurgitated by owls underneath theirresting sites) and carnivore scats and skulls may also be found by searchingrubbish tips near villages (Barnett, 1992). Hair analysis is another usefulmeans of identifying small mammals indirectly; indeed, sampling of carnivorescats in order to identify the remains of small mammal species is a proventechnique. In Central African Republic, Ray & Hutterer (1996) found that therewere 16 species of sympatric shrews in one 35km2 study area just by analysingcarnivore scats collected over a two-year period. They attributed this highlyunusual diversity less to some incredibly feature of the site, but rather becausecarnivores, as a moving trap, represented a more efficient capture techniquethan conventional pitfalls. With detailed information on hair size, colour andstructure (e.g. scale patterns), one can even design fur traps with sticky tape ortiny snags placed on tubes through which animals pass, to enable the samplingof hairs for subsequent identification to species.

For bats, high-frequency bat detectors can be used to investigate thepresence of insectivorous bats, and indicate where future trapping might focus.However, a reference collection of bat calls is needed to relate the calls to aparticular species (see Wilson et al., 1996).

4.3.2 Bat roost surveysWhen a bat roost has been located, there are two approaches that can

be taken to estimate the numbers present, namely emergence counts androost counts. The emergence points from caves, for example, need to belocated, and observers stationed at each in the late afternoon so that they cancount how many bats emerge at dusk. Each observer should have a watch and

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tally counter. All bats exiting and entering should be counted in convenient timeunits (e.g. five-minute intervals), and those that return to the cave (presumablyto come out again) are deducted from the total. Care needs to be taken to dis-tinguish between different species leaving the same roost. This may be feasiblewhen only a few easily-distinguished species are present at a roost, but mightbe extremely difficult or impossible when closely related species, similar in size,shape and behaviour are present. If there are several hundred bats emergingthen counts become less accurate, and more observers (coupled with photo-graphic techniques) can be used to improve the accuracy of the counts(Barlow, 1999).

Counting bats that are roosting in enclosed areas (e.g. in buildings) canbe done using low lights and binoculars to make total counts, and tree-roostingfruit-bats can be counted directly in the daylight (Kunz, 1988). As the colonysize gets larger, counting becomes more difficult, and sub-sampling of differentsections of the roost (with different concentrations of bats) may be needed. Forexample, numbers of fruit bats in many trees may be estimated by counting asample of trees and multiplying up by the number of occupied trees once amean (plus standard error) number of bats/tree has been established.

4.3.3 Live-trapping: rodentsand insectivores

There are numerous reviews of this method of census (Delany, 1986;Barnett, 1992; Wilson et al., 1996) and this section summarises the mainmethods as they relate to forest survey work in Africa.

Equipment� string and flagging tape� specimen bags and polythene bags� sedation materials� gloves� equipment for marking animals� spring balances� traps (see below) and bait

There is a wide range of live-traps to select from (Fig. 4.1):� At the smaller end of the range, Longworth and Sherman live-traps

are mostly made of aluminium, and measure approximately 230mm x95mm x 80mm in size when set up. These traps are very lightweight,and Shermans have the added advantage that they can fold flat for storage and easy carrying in the field.

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� Havahart live-traps (available from international suppliers) are effectivefor sampling species such as African giant rat, and hyrax (dassie), andare convenient and easy to use. However, they are not collapsible andthus rather bulky.

� Pit-fall traps are important to catch mammal species that may not be caught in other types of live-traps. This includes species that do not like the baits on offer and/or species that forage widely and do not follow runs (including shrews and other insectivores). Shrews are probably better surveyed using pit-fall trapping (section 3.3.2).

� In the case of elephant-shrews, animals can be driven out of their nests into encircling nets (2m-wide fishing nets), once the nests have been located (see details on antelope drives – section 5.3.2).

� The presence of nests along transect surveys has been developed as an indirect index of abundance (Fitzgibbon and Rathburn, 1994), usingthe same principles as described in the next chapter (section 5.3.3).

Site selectioni) Rodents tend to move around the edge of clearings, and beneath fall-

en logs and rocks. They also follow runs which may be visible, including alonglow branches and lianas, and their holes are often at the base of trees androcks. They also use places to gather, store and consume foods, and toshelter. All these are potential trapping sites.

ii) Once a trapping system has been developed, then every effort shouldbe made to keep the same site selection procedures, and the number andtypes of traps consistent between different trapping periods (e.g. over consecu-tive years), or between sites in the same period. For example: 20% on lianas,80% on the ground; 50% box traps, 50% break-back traps (see below).

Longworth

HavahartSherman

Fig 4.1: Live Traps

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Procedurei) Traps are generally placed in clusters, termed ‘trap stations’, spaced

regularly (5–10m) along a transect or in a regular grid. Each trap station canhave a number of traps, although three per trap station is probably a minimum.

ii) The traps have to be baited, and particular attention needs to be paidto standardising the baits. There are a number of baits that have been suc-cessfully used: peanut butter works well, and can be mixed with other items(e.g. banana, maize meal, oats, raisins, forest fruits, chunks of manioc root,dried fish, etc.). In Tanzania, KH uses pieces of fried coconut, mixed with localpeanut butter. This fits onto the trap bait-hook well, is attractive to rodents, andseems to survive the threats posed by rain and ants. The selection of bait willhave a major impact on the species that will come to the trap, so the same baitneeds to be used if trapping is to be standardised between sites.

iii) If it is rainy, then some bedding (pieces of old newspaper) can beadded to the box traps to reduce the risk of hypothermia. However, care mustbe taken in the process of preparing traps not to leave human scent which maydeter animals from entering – rubbing other smells (e.g. meat fat) onto the trapis one option, but minimising handling and airing traps is always wise. If previ-ous trapping has left urine or blood on traps, it is advisable to wipe/wash thisoff. Indeed, it is good practice to thoroughly wash traps to remove old bait,rodent urine, etc. prior to storage (see also the traps described in section 4.3.6).

iv) The traps can now be placed in suitable trap sites, and need to besecured with strong string or stakes so that they are not moved either bytrapped animals or, on rare occasions, by predators trying to get to the trappedanimals. Trap entrances/surfaces should be flush with the substrate, so thatanimals do not have to go uphill to be caught, and they must not be easilyflooded (or washed away) if there is sudden rain.

v) Mark each trap site with flagging tape, and give each trap, trappingstation and trap-line a unique number.

vi) The traps must be inspected in the early morning, midday and lateafternoon. If it is cold or wet, then more frequent inspections are advised.Ideally standardise the procedure so that all traps are baited and set between,say, 18:00 and 19:00, and are inspected between 06:00 and 07:00 thefollowing morning.

RecordingThis section applies to all small mammals, including bats, caught in

live-traps.i) The following should be recorded on a standard trapping record

form (Form 4.1) at the beginning of each transect:

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� full name of surveyor; sheet reference, which could refer to the fieldnotes recording system (e.g. 3 or 12); date (dd/mm/yyyy); and addressof institution that has a copy of the field records and specimens col-lected; collector number.

� survey site: the name of the region/forest area, and site within the for-est, where the survey was conducted (e.g. Kakamega Forest Reserve,Ischeno area); altitude (in metres above sea level); aspect (e.g. is the terrain steep or flat; valley-side, ridge-top or valley-bottom; facing north, south, east or west); latitude and longitude, in degrees, minutesand seconds (if available, using GPS), and the UTM (metric grid) can also be added here (two letters, followed by six numbers).

� season: wet or dry season.� lunar phase: what quarter of the moon is it, and is it getting larger

(waxing) or smaller (waning).� vegetation: use terminology that is accepted internationally, in particu-

lar make use of White’s (1983) phytogeographic regions of Africa.Other national and regional categories can also be used.

� any indications/signs of human disturbance.� weather: a statement about the weather during the trapping period

(e.g. clear, clouds, rain, overcast, windy).� temperature: typically the minimum night-time temperature.

ii) Record all the traps that were set off during the night, making a note of the following:� trap lines/trap no.: the trap location can be cross-referenced to a map

of the survey site.� trap type/bait: type of live-traps/nets or snap traps successful, and

what bait was used.� microhabitat: this refers to details of the trap location – beneath a log,

at the base of a tree, on a low branch, in burnt land, tied to a liana, inleaf litter, etc.

� water association: whether the trap is situated near water bodies (e.g. 5m from stream edge) and the type of water association (e.g. stream, river, marsh, pond, dry river bed, etc.)

� topography: e.g. ridge top, halfway up hill, bottom of hill, valley, path, plain, and so on.

� species captured and corresponding specimen sheet no (see iii). Use the scientific name of the species where identification is certain and record the English name where possible. Follow a standard list when using Latin names.

� If the trap has been set off but no species has been captured, this should be recorded under ‘Other’. Note whether bait has been

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removed or partly eaten and if traps have been moved. If a species has beencaptured, use the Other column to record information such as dominant plantsin the immediate vicinity or any other important observations.iii) When an animal is caught, it is important to record as much informationabout the animal’s condition as possible on standard forms (Form 4.2; occa-sionally, specimens may be collected for preservation purposes, see section4.4).iv) Care must be taken not to injure or traumatise the animals during thisprocess, and to minimise risk of disease or infection spreading to surveyors(see section 4.5). Thick gloves are important, and surveyors should learn howto hold captured animals without injuring themselves or the animals. Captivescan be sedated by carefully emptying the trap into a large polythene bag con-taining a small piece of cotton wool soaked in chloroform or ether. The animalshould be drowsy, but not unconscious, when it is picked up for inspection.

Data analysis is discussed in the subsequent section.

Fig 4.2: Handling small rodents

4.3.4 Live-trapping: batsAlthough the same equipment will be required as for the live-trapping of

rodents and insectivores, the trapping system for flying mammals obviously isentirely different. There are three basic bat-catching techniques:

Hand netsHand nets (made with mosquito mesh if necessary), with long handles, a

deep net, and firm rim can be used to catch bats. This can be done by holdingit over a small hole through which they are emerging, or placing them overroosting bats on ceilings and cave walls (Barlow, 1999). Hand nets can also beused to catch flying bats by bringing the net quickly around the bat from behind(Wilson et al., 1996), although this method should be used infrequentlybecause it runs the risk of damaging the bat’s wings.

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Mist netsMist nets for catching Microchiroptera should have a mesh size of about

36mm but stronger nets, with larger mesh sizes, are needed forMegachiroptera. Mist nets come in varying lengths of 6–18m. Monofilamentnets should not be used for catching bats (Barlow, 1999). Discussions aboutmist netting are given in the chapter on bird surveys (section 7.3.8), includingdetails of all the equipment needed.

Mist nets tend to be most effective in catching medium and large bats,especially plant-visiting species travelling in the understorey of the forest.Smaller insectivorous species tend to evade mist nets, and quickly chew theirway out when caught.

The advantage of mist nests is that the nets are easily transported inbags to the field site, as long as large numbers of lightweight bamboo or alu-minium poles are not needed. In addition, the surface area for catching can beenlarged by stringing a number of nets together.

The main disadvantage of mist nets is that they are hard to move onceset up. It is also a slow and tricky business removing bats from the nets, duringwhich time both the bats and the nets can get damaged.

Harp trapsHarp traps have been developed in the last 30 years, and operate on the

principle that bats have difficulty in seeing – either visually or by means ofecholocation – thin strands (Kunz et al., 1996). They are most effective incatching smaller, insectivorous bats.

To make a harp trap, a rectangular frame (approx. 2m x 2m) is construct-ed, and vertical lines are attached at the top and bottom, 25mm apart (theharp). Monofilament fishing line (about 300g strength) is readily available forthis purpose, although steel wires have been used. A second frame, with thesame layout of lines, is fitted 70–100mm away from the first frame, with thevertical lines on the second frame corresponding to the gaps between the lineson the first frame (see Fig. 4.3). Bats fly into the trap and get blocked betweenthe two sets of lines, causing them to fall or flutter into a canvas bag at thebottom of the trap. The canvas bag needs polythene flaps on either side of theentrance, leaving an open slit through which bats will fall, and under which thebats can rest in a dry place.

Trapping efficiency can be increased by having three or four layers oflines on a single trap (Francis, 1989), and the traps can be made as large asconstruction materials and access to forest survey sites allows; a trap used tocapture flying foxes was 15m high and 17m wide (Wilson et al., 1996). Sometraps have legs to stand them up on the forest floor, but others are hung fromtree branches using ropes and pulleys.

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The advantage of harp traps is that they can easily be moved about toother catching sites within the survey area, and bats can be removed fromthem quickly. The disadvantages are that they generally offer a small surfacearea for trapping, and can be bulky to carry into the forests in the first place.

Site selectioni) For mist nets and harp traps, the entrance to roosts is an obvious

place to survey, although the roost exit should not be completely blocked andcare should be taken not to catch more bats than can be safely removed fromthe nets/traps.

ii) Other suitable sites include beside, or stretched over, small pools andstreams, or any flyways that bats appear to be making frequent use of. Thebest places are where there is a gap in the vegetation that funnels bats into anarrow area where nets/traps can be placed. Placing traps/nets at right anglesto each other, or in a V-shape, may improve catches.

iii) Catching bats in the upper strata of the forest, or above the treecanopy, obviously requires nets/traps to be hung from branches, or from aerialwalkways that have already been constructed. Time is needed to fire stringsinto the canopy trees (with bows, cross-bows or sling-shots), and to haul up thenets/traps in such a way that they hang securely and do not get caught up intwigs and branches. Safety and specialist equipment are needed if climbersare clambering up the trees to set the nets/traps.

iv) Bats learn to avoid places where traps/nets have been set, sotraps/nets need to be moved periodically (every 2–3 days), or as soon as thereis an obvious decline in the number of catches.

Fig. 4.3: A harp trap

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Procedurei) Nets and traps should be set up well before sunset, so that they are

ready for the initial surge in bat activity at around dusk. In the case of mist netsthis means that any birds caught before dusk need to be removed.

ii) Nets and traps should be checked at least every 30 minutes. If toomany bats are being caught then traps/nets should be closed so that bats don’tget damaged. They should also be closed if it starts to rain – bats die veryquickly if they get cold and wet.

iii) Although trapping efforts should be concentrated around dusk andearly evening, it is important to keep going throughout the night, or at differentperiods on consecutive nights until dawn, in order to cover all periods ofpotential peak activity for different bat species.

iv) Once a trapping/netting system has been established, it should bekept consistent between survey sites and periods (e.g. same number and sizeof nets/traps; same arrangement of traps/nets; same number of hours andperiods of the night sampled).

RecordingFollow the same procedures listed above for rodents and insectivores

(section 4.3.3; Form 4.1) being particularly careful while handling live bats.

Fig 4.4: Handling bats

Data analysisThis section applies to all small mammals, including rodents and insecti-

vores, caught in live-traps.At a most basic level, a list of the number of species caught can be used

as an indication of biological richness for those species that can be trapped.Species lists can be built up over time, and supplemented with records fromother trapping/survey procedures.

Some rudimentary indices of abundance have been developed to makeuse of trap records. These indices present data in terms of the trapping suc-cess for a given trapping effort, often expressed as catches per trap-night (trap-nights = number of traps multiplied by the number of nights set), or catches pertrap-hour, etc. In the case of bats, reasonably accurate population estimatescan be obtained if a sample of 350–500 bats is caught (Barlow, 1999).

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Advantages/limitationsi) For all but the largest species, there is little option but to trap small

mammals to carry out surveys. The constraints on this approach are the effec-tiveness of different types of traps to catch the full range of species present,and the ease/difficulty of getting the traps into remote forest areas.

ii) At the level of generating a species list, the results reflect the pres-ence of those species that are prepared to enter traps (for that bait). Theresults are therefore limited to giving information on the species richness ofonly those species for which the methods are suitable.

iii) The same applies for population estimates. However, once an effec-tive trapping system (including trap-siting, bait, etc.) has been developed for aspecies, then mark-recapture methods can be used to estimate absolute pop-ulation densities, and make comparisons over time or between sites.

4.3.5 Capture, mark, recaptureIf a long-term study is planned, then mark-recapture techniques can be

used to make better estimates of population size. In this approach, animals arecaptured (using one of the methods described above), marked, and released,and the population sampled again after some time, using the same trappingmethods. The population estimates are based on the equation:

Total population = total first catch x total second catchnumber of recaptured marked animals

However, a number of key assumptions must be met for this to follow(after Kunz, 1988):

� survival rate of marked individuals is representative of the population as a whole;

� the probability of survival between capture periods is equal for marked and unmarked individuals;

� the permanent loss of individuals from the population is a result ofdeaths, and not long-term emigration (or dispersal);

� marked individuals have an equal probability of being captured as unmarked animals;

� marks are not lost;� the intensity of trapping (number of traps, number of days trapping,

etc.) is the same in different surveys.

These requirements are often not met, especially during a generalsurvey of many species in a short period.

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More detailed ecological research, with reference to other survey books(e.g. Wilson et al., 1996), should be made before attempting this detailed levelof analysis. The references give details of the mathematics of the surveyapproach, as well as different ways to mark animals before they are releasedafter capture (e.g. clipping rodent toenails; fitting bands onto bat forewings;using luminous dyes and permanent markers on fur, etc.). Reference shouldalso be made to computerised data analysis systems, such as CAPTURE(Pollock et al., 1990; obtainable from http//www.mbr.gov/software.html).

4.3.6 Removal or dead-trappingFig 4.5: Snap trap

EquipmentIn addition to the equipment necessary for live-trapping (section 4.3.3),

the following should be borne in mind regarding the use of traps fordead-trapping:

� Important considerations when selecting traps include: whether their different parts are susceptible to rust, or rotting of wooden parts; whether the spring is too strong, and is therefore likely to destroy the specimens (loosening springs by one turn can resolve this problem); whether they have serrated edges which can severely damage specimens; whether they are too small to make a clean kill of medium to large species.

� Rat-size traps take up space and are heavy. If packed in such a way that they become bent or the triggers are damaged, they will not be effective. It is therefore important to pack them as com-pactly and as securely as possible.

� When storing traps, metal traps can be painted with red oxide primer to reduce rusting, and wooden traps can be dipped in linseed oil, which reduces their tendency to soak up water in the field (and increases trap life); as far as is known, the strong smell of this oil has no negative effect on capture rate.

� There is a wealth of locally-made traps which can also be used, and which can improve the range of species being trapped in an area. Although there are also local trappers adept at operating these traps, the variability of trap construction usually precludes using these traps for systematic surveys in different forests.

� Try to select a type of trap which is available in large numbers and which is likely to be available for purchase in the coming years.

Procedure and recordingThe principles described above for live-trapping rodents and insectivores

(section 4.3.3) all apply to trapping with break-back traps.

Advantages/limitationsBreak-back traps are much lighter and more compact to transport than

live-traps. The standard break-back traps used to kill pest species such as rats(larger size) and mice (smaller size) are widely available, and can generally bepurchased in the country where surveys are to be carried out. They generallycatch more than live-traps, thereby providing specimens for identification andmuseum reference collections.

However, they are indiscriminate in what they catch (i.e. they are notspecies-specific); usually, many individuals of one or two common species willpredominate. Thus, many individuals are killed for a minimal amount of infor-mation that may be useful for management, a problem exacerbated whendoing surveys in conservation areas where protection may be a focus of man-agement. The catch is also strongly influenced by the baits that are used, andthe ecology of the species in the forest site.

4.4 Specimen handlingSpecimens collected from break-back traps can be supplemented with

those from live-traps. If an animal has been live-trapped, and examined, theanimal may be killed by cervical vertebrae dislocation, thoracic compression orany other humane means. Barnett (1992) has offered some guidelines on whenanimals might be killed:

� when the animal is injured (physically or mentally) in live-traps and mist nets, including wet/cold animals that are hardly moving;

� to obtain reference specimens (voucher specimens) that can be used for the later identification of species;

� where specimens of identified species are needed for referencecollections (for example, if it is found in a new region).

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There is a wealth of information that needs to be collected from deadspecimens. Some of this can be done in the field, but further research may berequired back in the laboratory (Wilson et al., 1996). Since specimens arerequired for accurate species identification, it is very important that surveyorstake time to visit museum or university specimen collections in order to becomefamiliar with hair/skin colouration, and other diagnostic features for speciesidentification, especially cranial/dental anatomy. Discussions should be heldwith curatorial staff to get advice on what needs collection, how to measuresmall mammals accurately, how to prepare specimens, and get copies of theirstandard specimen record sheets and identification guides.

Equipment� dissecting kit: scissors (fine and thick), scalpel (including different size

blades), forceps (fine and thick), syringes (with fine and thick needles),surgical mask and gloves

� ruler/callipers� Pesola weighing scales� waterproof specimen labels� thick thread and sewing needles� plastic screw-top storage jars� muslin/paper towels� alcohol (70% ethanol) and/or formalin

Recordingi) Confirm the identity of the species and give the animal a field number.

Unless these are supplied by your institution, it will be most convenient if youuse a series of numbers that is preceded by your initials (e.g. CAM 305). Enterthis on the data sheet (Form 4.2) and, if you are not using pre-numbered labeltags, on a tag. A specimen without a label indicating the date, place of collec-tion, and collector, has little value.

ii) It is critically important to use label paper that will withstand field andstorage conditions. If the specimen will be prepared as a study skin, standarddry label tags are available. If it is to be preserved in fluid (formalin or alcohol)then special water-resistant paper must be used for the labels. Furthermore, itis critical to use either a hard pencil or waterproof ink (use either Indian orPigma felt-tip pen) on the label. If ink is used, make certain that it will not dis-solve in the fixative. Be certain that it is completely dry before immersing it inliquid. It may be necessary to dip the label in fluid first, and then dry it beforeimmersing the specimen.

iii) Examine whether the animal is male or female (if possible), try toassess age (e.g. infant, juvenile, subadult, adult, old) from size and/or tooth

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wear, and note other features such as: pregnant or lactating females; breedingcondition (i.e. is the vagina perforated); colour and markings (such as stripesand spots, including variations); presence of wounds on ears, tail, and else-where; dental formula; mammary formula; and parasitic infections (collect spec-imens if required); etc.

iv) Take standard length measurements in millimetres: Head and Body(HB); Total Length (TL); Tail Vertebrae (TV), Ear (E) and Hindfoot (HF) (seeFig. 4.6). The hindfoot measurement usually includes the claw, i.e. HF/cu (cumunguis) but a few workers measure the hindfoot excluding the claw (sineunguis); we include the claw in our measurements. For bats, two additionalmeasurements may be used: Length of Forearm (FA), and Length of Tragus(TR) – the latter is a prominence in front of the exterior opening of the ear.Body mass in grams (W) is measured using a spring balance of the appropri-ate scale. Make a note of any material that is preserved (e.g. skin, skull, blood,muscle tissue).

Fig. 4.6: Measurements for small mammals

ProcedureProper specimen preparation in the field is necessary to ensure that any

mammal that dies, either as part of the process of collection for voucher speci-mens or incidentally by injury in a trap, being eaten by safari ants, or rotting inhot temperatures, is preserved, labelled and the data used. A specimen is oflittle value without a good label, so it is critically important to prepare yourspecimens carefully and label them well.

Wet specimensi) If the specimen is to be prepared as a fluid specimen (i.e. fixed in

formalin and later stored in alcohol) then a small numbered tag is usually tiedon the left hind foot.

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ii) After the measurements have been taken and the number tagattached, the body cavity is cut open using scissors or a scalpel; this allows thefixative to enter the body cavity and gut as quickly as possible. If the animalhas a very full stomach, it may be necessary to inject formalin or alcohol intomuscle masses and into the stomach and/or intestine. Ideally, this is the time tocarefully examine the reproductive tracts of females and record the condition ofthe ovaries and uterus, number of foetuses, and uterine scars.

iii) Because the skull is so critical to the identification of many smallmammals, some workers at this stage remove the skull from the carcass andstore it in 70% ethyl alcohol. The skull should be tagged with a small labelbearing the same number assigned to the animal, and kept with other suchskulls. Later, when dermestid beetles are used to clean the skull, they will hap-pily devour the skin and muscle off such a specimen. Such is not the case formaterial preserved in formalin, which the beetles do not seem to like the taste of!

iv) Information on what animals have been eating can be obtained fromthe stomach contents, and other parts of the intestine or the faeces. The stom-ach contents should be analysed one by one, and proportions of volume attrib-uted to different seasons (e.g. 50% seeds; 20% insects; 30% plant fibres).

v) Wrap specimens in muslin or paper towels before putting them intothe storage jars to reduce the risk of damage during transport. Make sure thatthe preserving fluid is topped up and of sufficient strength; it is necessary tohave a large volume compared to that of specimens.

vi) If there is an opportunity to send tissue samples to laboratories forgenetic and cellular analysis, then the laboratory will give clear instructionsabout how to prepare the samples.

Dry specimensi) Small mammal skin preparation is a standard procedure, and involves

removing muscles and other tissues which are likely to rot, and stuffing thebody with material (such as dry cotton wool) so that the body retains a normalshape.

ii) Skins need to be pinned out and dry on both sides, but they shouldnot be smoked (this will affect both skins and labels). Cover with cheesecloth tokeep flies from laying their eggs on the skins. Beware of potential predators,such as insects, dormice, and other rodents, as well as birds of prey such askites and ravens; the latter have even been known to remove covers of tins,etc. to get at specimens! Once skins have been dried (if they are sufficientlydry, the skin will crinkle and the ears will be stiff) then they can be packed fortransport.

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iii)Drying skins in forest conditions is very difficult as they are liable toinsect attack and rot very quickly. If wet specimens cannot be prepared, thenconstruct a drying oven using hurricane lamps and metal tins or buckets. Thiswill ensure that specimens are quickly dried, but care must be taken not to charor smoke the skins. They can then be packed into plastic bags to prevent themabsorbing the damp, along with some naphthalene crystals (mothballs) toreduce risks of insect attack.

iv) It is usual to preserve some specimens of each species as skeletal;these have most of the large muscles removed, and are then dried. Or, if theyare in a very wet situation, as may arise in a rain forest, the skeleton can belabelled and placed in 70% alcohol.

4.5 Health and safetyThe close proximity of surveyors to small mammals during trapping work

means that care has to be taken to avoid the spread of infection or diseases.Rabies is a risk in Africa, and there are probably many arboviruses (arthropod-borne viruses) that might potentially be found in small mammals and theirectoparasites. Plague, a bacterial disease transmitted by fleas, is endemic inparts of Africa.

For these reasons, field workers should take care to avoid being bittenby small mammals, and, if surveyors are bitten or scratched, lacerations shouldbe treated immediately with antiseptic and bandages. Even with dead animals,care needs to be taken not to get scratches during specimen processing.Always wear a face or surgical mask and protective gloves when collectingtrapped animals and preparing specimens (to avoid being bitten by anyectoparasites, such as fleas, ticks and lice), or when doing carnivore scatanalysis (for indirect evidence of occurrence).

4.6 ConclusionsThere is a wealth of methods that can be used, and adapted, in order to

survey small mammals. All require capturing the subjects of a survey, so acombination of methods should be selected to ensure that those mammals thatavoid one method are captured with another.

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4.7 ReferencesBarlow, K. (1999). Expedition Field Techniques: Bats. Royal Geographical Society, London, UK.

Barnett, A. (1992). Expedition Field Techniques: Small Mammals (excluding Bats). RoyalGeographical Society, London, UK.

Corbet, G.B. & Hill, J.E. (1991). A World List of Mammalian Species. 3rd edn. Oxford UniversityPress, Oxford, UK.

Delany, M.J. (1986). Ecology of small rodents in Africa. Mammal Rev. 16: 1–41.

Ferreira, S.M. & van Aarde, R.J. (2000). Maintaining diversity through intermediate disturbances:evidence from rodents colonising rehabilitating coastal dunes. Afr. J. Ecol. 38(4): 286–294.

Fitzgibbon, C.D. and Rathburn, G.B (1994). Surveying Rhynhocyon Elephant-Shrews in tropicalforest. Afr. J. Ecol. 32(1): 50–57.

Ferreira, S.M. & van Aarde, R.J. (1997). The chronosequence of rehabilitating stands of coastaldune forests: Do small mammals confirm it? S. Afr. J. Sci. 93(5): 211–214.

Francis, C.M. (1989). Comparison of mist nets and two designs of harp traps for capturing bats. J.Mammal. 70: 865–870.

Happold, D.C.D. (1987). The Mammals of Nigeria. Clarendon Press, Oxford, UK.

Hilton-Taylor, C. (compiler) (2000). 2000 IUCN Red List of Threatened Species. (Including CD-ROM). IUCN, Gland and Cambridge.

Hutson, A.M., Mickleburgh, S.P. & Racey, P.A. (Eds.) (2001). Microchiropteran Bats: Global StatusSurvey and Conservation Action Plan. IUCN, Gland, Switzerland.

Kingdon, J. (1974). East African Mammals: An Atlas of Evolution in Africa. (Vols 2A & 2B).Academic Press, London, UK.

Kingdon, J. (1997). The Kingdon Field Guide to African Mammals. Academic Press, London, UK.

Kunz, T.H. (1988). Ecological and Behavioural Methods for the Study of Bats. SmithsonianInstitution Press, Washington, USA.

Kunz, T.H., Tideman, C.R. & Richards, G.C. (1996). Capturing mammals: small volant mammals.In: Measuring and Monitoring Biodiversity: Standard Methods for Mammals, pp 123–146. (Ed. byD.E. Wilson, F.R. Cole, J.D. Nichols, R. Rudran, & M.S. Foster). Smithsonian Institution Press,Washington, USA.

Lidicker, W.Z. (1989). Rodents: A World Survey of Species of Conservation Concern. IUCN SSCOccasional Paper no. 4. IUCN, Gland, Switzerland.

Malcolm, J.R. & Ray, J.C. (2000). Influence of timber extraction routes on central African smallmammal communities, forest structure, and tree diversity. Cons. Biol. 14: 1623–1638.

Mickleburg, S., Hutson, A.M. & Racey, P.A. (Eds.) (1992). Old World Fruit Bats: An Action Plan fortheir Conservation. IUCN, Gland, Switzerland.

Nicoll, M.E. & Rathbun, G.B. (1990). African Insectivores and Elephant-shrews: An Action Plan fortheir Conservation. IUCN, Gland, Switzerland.

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Nowak, R.M. (1999). Walkers Mammals of the World. 6th edn. John Hopkins University Press,Baltimore.

Pollock, K.H., Nichols, J.D., Brownie, C. & Hines, J.E. (1990). Statistical inference for capture-recapture experiments. Wildl. Monogr. 107: 1–97.

Ray, J.C. & Hutterer, R. (1996). Structure of a shrew community in Central African Republic basedon the analysis of carnivore scats, with the description of a new Sylvisorex (Mammalia: Soricidae).Ecotropica 1: 85–97.

Rosevear, D.R. (1965). The Bats of West Africa. British Museum (Natural History), London, UK.

Rosevear, D.R. (1969). The Rodents of West Africa. British Museum (Natural History), London, UK.

Schlitter, D.A. (1989). African rodents of special concern: a preliminary assessment. In: Rodents: AWorld Survey of Species of Conservation Concern. (Ed. by W.Z. Lidicker). IUCN SSC Occasionalpaper No. 4. IUCN, Gland, Switzerland.

White, F. (1983). The Vegetation of Africa. UNESCO, Paris, France.

Wilson, D.E. & Reeder, D.M. (eds). (1993). Mammal Species of the World: A Taxonomic andGeographic Reference. 2nd Edition. Smithsonian Institution Press, Washington, USA.

Wilson, D.E., Cole, F.R., Nichols, J.D., Rudran, R. & Foster, M.S. (Eds.) (1996). Measuring andMonitoring Biological Diversity: Standard Methods for Mammals. Smithsonian Institution Press,Washington, USA.

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Form 4.1: Small Mammal Catch Records (instructions see p52)

Surveyor: Field sheet ref: Date:(total observers): (dd/mm/yy)

Address:

Survey site: Altitude: Aspect:

Latitude: Longitude: UTM (if available):

Vegetation: Human disturbance:

Season: Weather: Lunar phase: Temperature:

Other:

Trap line Trap type Micro- Water Topography Species & Other& no. & bait habitat association specimen

sheet ref.

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Form 4.2: Specimen Records: bats, rodents and insectivores

Specimen sheet ref: Field sheet ref:

Collector: Date: Time:(dd/mm/yy)

Address:

Collecting site: Altitude:

Latitude: Longitude: Slope:

Additional notes:

Species: Field no.: Sex (if known): Age:

Pregnant/lactating: Embryos: Breeding condition:

Colour/markings: Wounds:

Dental formulae: Mammary formulae:

Ectoparasites: Endoparasites:

Measurements: Bats: FA TRmm mm

HB TL TV E HF Wmm mm mm mm mm g

Material Preserved:

Skin Skull Skeleton Stomach Faeces Blood Liver Kidneys

Stomach contents:Component: Percentage:

Remarks/Other

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5.1 BiologyThis chapter will concentrate on the ungulates and the carnivores. Some

species are sufficiently abundant in African forests to allow direct counting ofanimals to estimate popuation sizes, but many others are rarely seen, andtherefore surveys rely on signs to assess their presence and gain a roughindex of their abundance. The signs include conspicuous footprints in softground; large or persistent dung piles; diggings, and broken or trampled vege-tation. This applies to many of the larger ungulates (see below), carnivores,pygmy hippo (Hexaprotodon liberiensis), and the pangolins or scaly anteaters,which live in burrows or tree-holes and feed on ants and termites.

Ungulates (Orders Proboscidea, Perissodactyla, andArtiodactyla)

Forest ungulates (mammals which walk on the tips of their toes) fall intotwo distinct size-groups. The small-bodied species (5-70kg) include duikers,chevrotain and bushbuck, which live in well-defined, stable home ranges.Larger species (>100kg) such as bushpig, giant forest hog, bongo, okapi, buf-falo, rhinoceros and elephant are often wide-ranging or even migratory. In gen-eral, ungulates have a keen sense of hearing and smell, but their eyesight isrelatively poor.

Duikers are the most commonly seen terrestrial mammals in manyAfrican forests, although daytime sightings all too often consist of a quick

5. Large and medium mammalsHelen Newing, Glyn Davies and Matthew Linkie

zebra duiker (Cephalophus zebra)

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movement and rustle in the bushes before you hear a whistle as they boundaway. Indeed, their shy and reclusive habit is one of the reasons why they areso poorly studied. For many years they were thought to be a homogeneousgroup of solitary, nocturnal, monogamous fruit-eaters, but research since the1980s has revealed that they vary considerably in ecological characteristics(Dubost, 1984; Feer, 1989). They have a varied vegetable diet including leafybrowse as well as seeds and fruits that fall to the forest floor. Some speciessuch as the blue duiker (Philantomba monticola) and the related Maxwell’sduiker (P. maxwelli) are active during the day. Others such as the bay duiker(Cephalophus dorsalis) are nocturnal, and the larger species (yellow-backedduiker, C. sylvicultor; Abbott’s duiker, C. spadix and Jentink’s duiker, C. jentinki)are active both by day and by night. Some species are solitary, some live inpairs, and others have been recorded occasionally in groups with one adultmale and a number of adult females (e.g. Maxwell’s duiker: Newing, 1994;Peter’s duiker, C. callipygus: Feer, 1989). All appear to have territories that aremarked with dung piles and musk from scent glands.

Large-bodied species such as suids (pigs), bongos, okapis, buffaloes,elephants and rhinos have lower population densities than duikers. They mayalso engage in seasonal migrations. Surveys of these species are thereforebased mainly on sign rather than direct sightings, as explained above.

Carnivores (Order Carnivora)All carnivores range widely relative to their body size – the larger the

species the further they range – and they live at low population densities com-pared with the herbivorous mammals on which they prey. African forest carni-vores range in size from the mongooses (300g to 5kg), genets and linsangs(500g to 3kg), otters, and the African palm civet (3kg) to the civet (c. 15kg),golden cat (c. 15kg) and leopard (c. 60–90 kg). Some open forest formations inEast Africa are also home to striped hyenas (c. 40kg). All carnivores have goodsenses of smell, hearing and sight and are seldom seen as a result. Populationsurveys of smaller species depend on trapping animals using fish and meatbaits (see previous chapter), whereas survey methods for larger cats includerecording pug-marks (tracks), scats, scrapes and kills, and the use ofphoto-traps.

5.2 Management issuesThere are a number of important management reasons to survey larger

mammals. From a conservation perspective, it is important to know how manyanimals are in different areas so that management plans can take account ofmigration routes and important locations for food or for refuge, as well as

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identifying areas with concentrations of animals that have potential for eco-tourism. Where animal populations are harvested, the effects of harvestingneed to be monitored to ensure that harvesting is sustainable. Furthermorethere are often conflicts between large terrestrial mammals and humans.Solutions to all of these management issues need to be guided by informationfrom biological surveys.

At a time when deforestation is accelerating across Africa, survey infor-mation is particularly important to assess and monitor the long-term effects ofhabitat changes. These range from complete loss of forest to minor vegetationchanges due to intermittent use. Forest clearance leaves fragmented islands offorest containing small populations of ungulates that are often not viable in thelong term. In contrast, selective logging can create patches of secondary vege-tation that benefit a large proportion of forest ungulates that are grazers ormixed browser-frugivores (although a few species do appear truly dependenton old growth forest).

Hunting and trapping heavily affect many forest species. Showy species,such as leopards and bongos, are hunted for their skins. Forest elephants,despite having smaller tusks than their savannah relatives, have long beenhunted for ivory. Duikers have been hunted and trapped for food for centuriesand are still the main source of fresh meat in many forested areas of Africa.Hunting and trapping have increased dramatically over the past few decades –partly because of rural population growth and partly because of increased tradeto supply growing markets in urban centres, facilitated by improved accessalong logging roads. As a result, although the smaller duiker species reproducequite quickly, their populations have been eliminated from many forest areasnear large human settlements and roads (Wilkie & Finn, 1990; Muchaal &Ngandjui, 1999; Noss, 1999); larger-bodied mammals reproduce the slowest.

In addition to human impacts on wildlife, large mammals can have a seri-ous impact on humans. Elephants are major crop pests and the cause of fre-quent complaint from communities near forest areas. Forest pigs and buffaloesalso cause problems for farmers, especially in terms of trampling and digging,and bushbucks eat vegetables in fields near villages. Leopards may prey ongoats, sheep and cattle. There must be a balance between wildlife conserva-tion and the control of animal pests, and to accomplish this we need effectivemonitoring of animal populations (Bell, 1984; Hill, 1998, 2000; Naughton et al.,1999).

On a more positive note, large mammals are an important resource fortourism development, and forest populations of elephants, bongos, rhinos, andto a lesser extent buffaloes, can be attracted to waterholes and saltlicks nearlodges for high-quality tourist viewing. However, surveys and monitoring areimportant to assess impacts of tourism on wildlife. A concentration of large

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herbivores at waterholes can cause serious damage to the surrounding vegeta-tion. Tourist trails can affect animal distributions in different ways – largeanimals, such as elephants and pygmy hippos will actually use these trails,because, like people, they find it easier than pushing their way through theundergrowth, but heavy tourist use and inappropriate behaviour by tourists (orby survey teams) may frighten animals away from the area. Conversely,species that are hunted may congregate in areas where there are tourists,because hunters are less likely to come there.

5.3 Methods

GeneralMammal surveys can provide three levels of data for managers. At the

most basic level they can determine the presence or absence of differentspecies at different sites in order to build up distribution maps. Information fromsuch distribution surveys (see section 6.3.1) is most valuable for rare or endan-gered species or for species that can be used as indicators of forest condition.At the next level of detail, simple sampling can be used to determine the rela-tive abundance of a species at different sites, or at a single site over time. Atthe third and final level, much more rigorous sampling, more extensive datacollection, and thus use of robust statistical analyses makes it possible in somecases to arrive at a quantitative population density estimate.

Surveys of terrestrial forest mammals are hampered because many ani-mal species are shy and secretive, hiding in the undergrowth. However, severalsuccessful survey methods have been developed to overcome this problem forsome groups. They can be divided into direct methods, which are based onsightings of the animals, and indirect methods, which are based on countingtheir signs. The rest of this chapter describes the various methods andindicates the strengths and weaknesses of each of them.

Seasonal variations in climate can result in dramatic changes in animalbehaviour, in visibility (according to density of undergrowth), and in the lengthof time that tracks and signs remain visible. Therefore basic surveys to deter-mine presence or absence of species may benefit from short visits in differentseasons, but any comparative studies should be restricted to a single season.

IdentificationA number of excellent field guides are available for identifying the larger

mammals of Africa. Dorst & Dandelot (1983), Haltenorth & Diller (1984) andKingdon (1997) all provide detailed information on identification, distributionand ecology. Other useful guides include Stuart & Stuart (1995, 1997) and

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Estes (1991). Although not a field guide, Rosevear (1974) is a useful referencefor identifying West African forest carnivores.

5.3.1 Hunters’ calls, attractantsand observation points

Hunters traditionally use a variety of snorts, calls and whistles to attractdifferent species of animals. The best example is the nasal bleat used to attractduikers, and researchers have used hunters’ calls to check for the presence ofdifferent duiker species (e.g. Wilson, 1990). The results can be impressive:within a few minutes animals will often come running to within a few metres ofthe caller. This technique is most successful if experienced hunters areemployed to do the calling, and they should not be accompanied by more thantwo surveyors. Calls should be made at distances of not less than 250m fromeach other. The surveyors should position themselves in an inconspicuousplace, such as between the roots of a tree buttress, and remain still and quietwhile the hunter calls.

Other attractants include natural or artificial salt licks for herbivores andmeat or scent stations for carnivores (see Blum & Escherich, 1979, for the lat-ter). It may take a few weeks for animals to find a newly-sited attractant, sothey are not suitable for quick, one-off surveys.

Equipment� camouflage-netting and string� machete, for construction of temporary hide

Site selectionStrategic observation points include: natural salt-licks, waterholes and

wallows, heavily fruiting trees, tree-fall gaps with a flush of new foliage, forestglades, logging roads, and areas with regular signs of tracks.

Procedurei) A simple hide can be built either with camouflage-netting hung

between trees or buttress roots, or by cutting the fronds of a palm tree to forma see-through wall. In protected areas, check to make sure this is not prohibit-ed. The hide should be located downwind of the observation site. Make surethere is a comfortable sitting place so that you don’t fidget. Alternatively, ratherthan build a hide, one can sit on a low branch in a tree or on a ridge or rockyoutcrop overlooking the forest floor below – few terrestrial mammals noticestationary objects above their heads.

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ii) Once a hide has been constructed it should be left for at least a daybefore being used, so that animals become accustomed to it.

iii) The best time to start watches for most species is just before dawn(so that you are settled down before the first light) or a couple of hours beforedusk. Approach the hide quietly from the opposite direction to the observationsite. Settle in a comfortable position so that you can keep still (use mosquitorepellent!).

iv) It is sometimes helpful to visit the ‘observation area’ to look on theground for footprints and other signs (hairs, dung, spoor, etc.), especially ifwatches are not producing many sightings. This can be done in the middayhours so that dawn and dusk watches are not disrupted.

v) A reasonable length of time for a first watch at a site is two to threehours. Leave the hide quietly, and in the opposite direction from the observa-tion area.

Recordingi) Fill in the survey data in the top section of the recording sheet (Form

5.1) before commencing the observation period. Give each survey site a name,and give observation points within each site numbers or codes (e.g. Surveysite: Gouleako; observation point 3). Record the type of vegetation, the degreeof human disturbance (which you may know from archival information or fromdirect observation), and any special features that may be relevant (e.g. riverineforest, mature lightly-logged, many-fruiting figs). Include altitude if you areworking across an altitudinal gradient.

ii) When one or more mammals are seen, note the time and watch quiet-ly for a few minutes, even if you can identify the species immediately. If theyremain at the site, begin to fill in the recording sheet (Form 5.1) very quietlynoting the time at the start of the observation, the species and the total numberof animals. Additional observations include the number of males, females andyoung animals, if known, and their behaviour. Make a note of any food eaten,and take a sample if necessary. If you cannot identify the animal species, writea detailed description in your notebook including an estimate of height, theshape (especially of the head and muzzle), horns (if present) and the coat pat-tern. Make a sketch of it.

iii) Remember to note down the time at which the animals leave. Whenthey have gone you can expand your observation notes and consult a mammalfield guide to check any species identifications you’re not sure about. Alsocheck the observation area for footprints, hairs, fallen fruits, etc.

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Advantages/limitationsThis is a time-consuming method, and should be undertaken only at

sites where there is evidence that animals are frequent visitors. Some skill isneeded in identifying suitable sites, and consulting local hunters and othersknowledgeable about local wildlife can save much time and effort. Within theselimitations, successful watches are a valuable and rewarding way to record thepresence of different species, to study behaviour, and to determine whethersites hold any potential for regular viewing by tourists.

There are several potential negative impacts of longer-term feedingsites. Animals may come to rely on being provisioned at the site, or they maybe placed in acute competition for the food at the feeding site. Alternatively,hunters may learn of the site.

5.3.2 Net drivesNet drives are used both for traditional hunting, for example in the

Central African Republic (Noss, 1999) and Zanzibar Island (Archer, 1994); andalso by researchers to catch small deer and antelope (e.g. Bowland, 1990;Newing, 1994).

There are inherent biases in the use of this method for determining pop-ulation abundance. For example, radio-tracking has confirmed that Maxwell’sduikers and red duikers sometimes move away from the nets or drivers beforethey are observed (Bowland, 1990; Newing, 1994). Some duikers, especiallyinfants, will be missed because they freeze in thickets and are not flushed outof their resting places. Nonetheless, net drives are sometimes the best optionto survey secretive ungulates, especially where thick vegetation makes directsightings difficult. The biases probably differ for different species, but can beassumed to cause an underestimate.

Net drives can also be extremely noisy and disruptive, and there hasbeen some concern about impacts on resident animal populations. However,evidence from radio-tracked animals has shown that they quickly return to theirterritories and resume their usual activities once the drivers have departed.

Equipment/personnel� tape measure� hunting nets (e.g. 50m x 2m; mesh 25–50mm; dark-coloured, elastic,

ideally with a breaking strain of at least 100 kg) � 60cm lengths of strong nylon cord attached to top of nets at intervals

of about 4m � machetes

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� large team (minimum of ten) of drivers/field assistants (with or without hunting dogs)

Site selectionWithin a survey site the region is stratified as described for transect sur-

veys (see below) and sample units are selected to cover the full breadth andrange of habitats.

Procedure and recordingi) If experienced hunters are taking part in the survey, it is best to follow

their normal method (see Noss, 1999), since it is likely that they are successfulat finding animals. Hunters usually enclose a large area (typically 4–5ha) withnets linked together.

ii) Where hunters are not involved the procedure will vary according tothe thickness of vegetation, the amount of netting available, and the numbersand knowledge of field assistants/drivers. Each drive usually covers 0.5–1.0ha.If the forest is quite easy to walk through and visibility is good, it may be suffi-cient to set up a single net-line immediately before the drive takes place, onone side of the block to be searched. Where vegetation is very thick, a grid oftrails (50m x 50m) should be cleared a few days before the drive takes place.This will allow the nets to be erected quickly and quietly and provide a sightingline for the monitors. In thick vegetation, it is advisable to net at least threesides of the drive area to make sure animals don’t escape unobserved. Themore nets used, the greater the time needed per drive, but the smaller thenumber of people needed to monitor the edges of the block.

iii) At the beginning of the drive, the field surveyors should surround theblock to be surveyed as quietly as possible. The 2m-high x 50m-long netsshould be erected by tying the nylon cords to trees at a height of 1.5–2 m,leaving enough slack on the ground to stop animals diving underneath. Oncethe nets are up, people should be stationed along three sides of the block withmost people on the sides that are not netted, close enough to each other sothat they can see clearly along the whole length of each side. This will be a dis-tance of between 15 and 30m, depending on the thickness of vegetation (theyusually need to be much closer together on the open sides). These people arethe monitors.

iv) The rest of the assistants form a line at one end of the block, oppositea netted side. These are the beaters. Once the nets are set up, the beatersenter the area and noisily dislodge animals from their hiding places by shoutingand banging trees, bushes and fallen logs with sticks. Dogs may also be usedfor this purpose, but they must be kept under strict control at all times.

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v) Some animals typically try to break back through the beaters, and sobeaters should be positioned closer together than the monitors (10–15m apart).The more people involved, the larger the area that can be included in a singledrive. Depending on team size and conditions, each drive (including setting upnets) can take anything from 30 minutes to two hours.

vi) Whenever an animal is detected the species and, if possible, age andsex should be noted. The sighting is called out to the neighbouring monitors toavoid animals being counted more than once. Any animals that are caughtshould be restrained and examined, noting age/sex and condition. Specimensmay also, under certain circumstances, be collected (see section 4.4).

vii) At the end of the drive, the team comes together to compare obser-vations and confirm the total number of animals of each species they haveseen. Basic information on the survey site, vegetation, weather and time ofdrive should also be noted; Form 5.1 can be used, omitting the first and lastcolumns.

Data analysisThe population density is computed as the number of duikers counted

divided by the area of forest sampled during the drives. During fieldwork, thecumulative density can be estimated at the end of each day of drives (by sum-ming results from all previous drives), and a graph drawn to get an idea ofwhen the density estimate stabilises and sample size is sufficient.

Advantages/limitationsNet drives are only feasible if a large labour force can be organised and

transported for a few days to the survey sites. If this is possible, the methodgives a large number of direct sightings and offers one of the most accurateways of getting population information for management purposes. In areas ofthick, secondary vegetation, it is sometimes the only option for surveys of ter-restrial mammals.

5.3.3 Survey walks: reconnaissanceand transect

The use of observation points or net drives is most suitable for concen-trated surveys in small areas of forest. To survey a larger area with relativelysmall survey teams (two or three surveyors) the only realistic option is to carryout survey walks through the area. Survey walks are used in two ways: eitherfor a ‘quick and dirty’ first assessment (a reconnaissance survey), or for a moremethodical evaluation of relative abundance or population density, through theuse of carefully positioned transects (straight trails). They can be based on

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either direct encounters with animals or indirect signs (footprints and dung –see section 5.3.4). It is not possible for a single surveyor to search thoroughlyfor both at the same time, but different members of the survey team canconcentrate on different aspects in order to maximise data collection from eachstudy site. Surveys should be carried out by night as well as by day, becausea) nocturnal species will be seen that otherwise might remain undetected; andb) many diurnal species such as blue and Maxwell’s duikers freeze whencaught in the beam of a strong torch, thereby allowing the surveyor to deter-mine age and sex of individuals.

To carry out transect surveys, new transects should be cut that are care-fully located in order to sample different vegetation types and levels of humandisturbance in proportion to their estimated occurrence in the study area. Theperpendicular distance of each animal or group of animals (or each dung pileor group of piles) from the centre of the transect is measured, so that an esti-mate of population density (or dung density) can be made. For population esti-mates, a minimum of 40 sightings per species in each habitat is necessary, andideally over 100 sightings should be used (Plumptre, 2000). Therefore, transectsurveys can only generate population estimates for species that are seen rela-tively often. In practice, sightings of all species are recorded, and different tech-niques are used to analyse data for each species, depending on the amount ofinformation gathered.

The procedure for reconnaissance surveys is similar to that describedbelow for transect surveys, but with two major differences – firstly in the sam-pling, and secondly in the lack of recording of perpendicular distances from thetransect. Reconnaissance surveys differ from transect surveys in that they ‘fol-low the line of least resistance’ through the vegetation in order to cover asmuch ground as possible. They may use existing human or animal paths, fol-low streambeds or concentrate in areas of sparse undergrowth where it is pos-sible to walk in a straight line without clearing vegetation (Walsh and White,1999). They consist simply of recording all encounters with animals and signfor a given distance walked. Vegetation types and levels of human disturbancecan be recorded during an initial reconnaissance survey.

Equipment/personnelTo set up transects� 30m tape-measure or topofil (hip-chain)� fluorescent vinyl flagging tape & marker pens� two machetes� team of four or more people (including two or more line-cutters)� maps, GPS, altimeter and clinometer if you are also undertaking

mapping

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To carry out transect surveys and reconnaissance surveys� one or, at most, two people� optional: optical range finder or survey laser binoculars

Site selectioni) As a general rule, transects should cover the main habitats present in

the same proportions as they occur in the study area. For studies in undis-turbed forest, this is usually done by using the bottom of the valley as the mainaxis and cutting transects perpendicular to it. For surveys of very large areas, aseries of baselines can be cut parallel to the valley bottom – for example, atintervals of 5, 10 or 50km – and transects can be cut perpendicular to eachbaseline. Transects should be a minimum of 2km apart (preferably more), andshould not cross each other. (See White & Edwards, 2000, Chapter 3, for fur-ther discussion of stratified sampling).

ii) Surveys that aim to determine the abundance of animal populations atthe regional level must usually include areas with different levels of humanactivity and habitat disturbance (farmbush, secondary forest, logged forest,undisturbed forest). If disturbance is likely to have a greater effect on mammalpopulations than watersheds (for example, where hunting or farming is veryintensive), it is more appropriate to use a road as the primary axis or to bal-ance sampling according to the distance from human settlements (e.g. Lahm etal., 1998).

iii) Once the approximate survey areas are decided, transects should bepositioned at least 300–500m apart and at least 500m from the base camp,because camp noises and smells often deter mammals (unless they aresearching your rubbish for food!).

iv) Large animals may use existing paths, so new paths should be cut forsurveying in order to ensure random sampling. However, cutting paths duringsurveys would frighten the animals away. As a compromise, new transects canbe cut a day or so before beginning the survey. If the cutting of new transectsis not felt to be justified and old paths are used, it is better to use narrow trailsthan wide tracks.

v) Using existing trails and roads is an efficient and useful way to checkfor the presence of species. However, using long-established trails that huntersand trappers follow, or logging tracks which have very different vegetation tothe rest of the area, will seriously bias survey results and influence populationestimates.

Procedure — cutting transectsi) Use a random number table to select a starting point and direction

(left or right) from the baseline for each transect. Alternatively, select the

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transect direction to pass through habitats of survey interest. The choice ofoptions will depend upon the overall aims of the study and the degree of habi-tat specialisation of the animals you are surveying. Each transect should be ofa length that can be traversed in a single session (typically 3–5km).

ii) Each transect should be cut perpendicular to the baseline, using acompass to keep it straight and the 30m tape or hip-chain to record the dis-tance cut. Slight detours around obstacles such as tree-falls are acceptable aslong as the original direction of the transect is maintained. If the vegetation isthick, two people should take turns at cutting. Record special features (hunters’camps, streams, etc.) as they are encountered, so that they can be mappedimmediately.

iii) Cut only the minimum vegetation necessary. If transects are going tobe used only during the day for a period of weeks, it is necessary only to makethe slightest clearance to allow movement through the area following a com-pass bearing (e.g. Walsh & White, 1999). If they are to be used at night, theymust be visible enough so that they can be followed easily without distractingfrom the search for animals during night censuses. If a long-term study site isbeing created, trails should be cleared sufficiently so that they will need onlyminor maintenance.

iv) Mark the distance along the transect every 50m. If transects are onlygoing to be used for a few months, write the distances on pieces of fluorescentvinyl marker tape and tie to saplings by the side of the path. If permanent tran-sects are being set up, paint the distances on trees, or nail numbered alumini-um tags to tree trunks.

v) Allow newly cleared transects to rest for at least one whole daybefore beginning surveys. This will let animals recover from the disturbanceand return to their normal haunts and habits. This is also a good time to draw asketch map of the transects.

vi) As a precaution against opening up new areas of forest for huntersand trappers, the starting point of a transect may be disguised so as not todraw attention to the new path, or may be started 50m inside the forest (froma road or logging track). Some surveyors even cut transects with secateurs sothat no path is left after them. If the transect is not going to be re-used, all dis-tance markers should be removed at the end of the survey period.

Carrying out surveysi) Daytime surveys should preferably be carried out in the mornings from

just after dawn to about 11:00, when animals are most active. If time is short,additional afternoon censuses can be carried out between 15:00 and 17:30,after which visibility becomes very poor. Night-time surveys can be conductedat any time during the night, but 20:00 is a common start time.

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ii) Do not carry out surveys in the rain: it will be harder to pick upsounds, and will affect the behaviour of animals (and surveyors!). If it begins torain, pause the survey until the dripping stops, or if it seems to be likely tocontinue, discontinue the survey.

iii) Ideally, transects should be walked by a single observer in the day-time, or by two observers at night. Walk very slowly, looking from side to sidefor movements and listening intently for sounds in the undergrowth, animalcalls or gnawing sounds. Aim for an average speed of about 1km per hour,including a pause every 100m or so to stop and listen. Additional time will betaken to record data when animals are sighted. Each transect should thereforetake between three and five hours.

iv) Accurate distance estimation is essential, and the use of an opticalrange finder is recommended (see also section 2.5).

v) If possible, rotate observers between transect lines to cancel out idio-syncratic differences. It also makes it more interesting and gives everyone thechance to see unusual tracks and signs, which can be marked with fluorescenttape.

Recordingi) At the start of each transect walk, fill out the top part of the form below

(Form 5.2). When one or more mammals are sighted (and often this will be ofanimals in flight), complete the columns in the second part of the table.

ii) The perpendicular distance is taken from the position at which the ani-mal was first detected to the nearest point on the transect, thus it may be nec-essary to walk along the trail to reach the correct point. It also may be neces-sary to approach the animals quietly in order to get a clearer sighting.Additional observations can include the number of males and females, andpresence of infants, activities and behaviour, and association or interactionswith other species.

Data analysisi) Relative abundance: for species where sample sizes are too small to

allow estimates of population density to be made, the number of animalsencountered per kilometre walked gives a rough indicator of abundance.

ii) Estimating population densities from line transect censuses involvescomplex mathematical modelling of the likelihood that animals are detected atdifferent distances from the transect. However, these statistical analyses canbe executed by the custom-made computer program DISTANCE, which isdownloadable from the internet (www.ruwpa.st-and.ac.uk/distance) and shouldbe used in conjunction with the accompanying book (Buckland et al., 1993).

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Analysis rests on several assumptions: � that transects are placed randomly with respect to the distribution of

animals;� that all animals on the line (strip width) are always detected; � that animals are detected at their initial location, i.e. prior to any

movement in response to the observer;� that measurements of perpendicular distances (animal-transect,

observer-transect) are exact.It is rarely the case that all of these assumptions are met perfectly, which

means that population estimates must be treated with some caution. For a fullreview of the key issues on theoretical aspects of analysis, and how to dealwith discrepancies, see Buckland et al. (1993).

Advantages/limitationsThe main advantage of reconnaissance surveys is that they are quick.

Also, they can be carried out during routine activities such as patrolling by parkguards, so lend themselves to monitoring. The main disadvantage is that sam-ples are likely to be biased in terms of habitat and intensity of human use.However, some studies of elephant dung and gorilla nests have comparedresults of reconnaissance surveys and full transect surveys and have found ahigh level of correlation. The general rule is that recce surveys should bebacked up by some formal transect surveys in order to evaluate any biases(Walsh & White, 1999; White & Edwards, 2000, Chapter 13).

5.3.4 Indirect methodsWhen the survey subjects are not seen directly, or seen very rarely, then

indirect survey methods are needed. This means that surveys are made for thesigns left by the animals, and the population density of the animals producingthe signs is estimated. Signs include faeces (e.g. pellet piles of duikers, dungpiles of elephants and buffaloes, scats of cats), footprints or spoor, hairs, dig-gings and nests (for pigs), urine-marking sites (pygmy hippo, rhinoceros andcarnivores). In this section, attention is focused on three approaches: dungcounts, track counts, and photo-traps.

A. Dung countsAnimal population density can, in theory, be calculated from dung density

on the forest floor according to two variables:� The number of dung piles produced per animal per day (defecation

rate).� The length of time the dung takes to disappear (dung-decay rate).

Unfortunately these two variables are affected by several different factors, and

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this introduces many potential sources of error. In addition, for groups such asmedium-sized duikers or small carnivores it is difficult to identify dung tospecies level. For example, only biochemical techniques will enable identifica-tion between the scats of golden cats and mongooses. Defecation rates varywith diet (e.g. White, 1995), and, in the case of big cats, with the oestrouscycle of females. Decay rates vary with the weather, microclimatic conditions,and with dung beetle activity. In Ugandan forests, for example, Nummelin(1990) showed that duiker pellets were encountered less frequently when rain-fall was high prior to surveys.

Any errors in estimation of decay rate and defecation rate will have aradical effect on the estimation of population density (Plumptre, 2000).Furthermore, territorial species such as duikers and carnivores use droppingsto mark their territories, so distribution of dung is not random, presenting com-plex sampling problems. In the case of migratory or far-ranging species suchas elephants, the survey area may not cover their whole range, so dung densi-ty will vary according to the passage of elephants through the survey area inthe period prior to the survey.

However, in spite of methodological difficulties, dung counts may be thebest option available for surveys, since dung is the most frequently encoun-tered sign of many larger forest mammals. In an effort to address the con-straints, detailed techniques have been developed to use dung counts for sur-veying forest elephants (Barnes and Jensen, 1987), and similar methods havebeen used for species ranging from buffaloes to duikers. If dung density is veryhigh, it may be possible to do away with the need to consider decay rates bysurveying the same transects repeatedly and clearing them of dung after eachsurvey. The number of piles produced for the unit area surveyed within aknown time period (i.e between the two consecutive surveys) can then berecorded (Plumptre, 2000).

For elephants, density estimates from dung counts have been shown tocorrelate well with those from other methods (Barnes, 2001). In general, how-ever, the smaller the species the less useful the method, because decay ratesare much more variable (see Plumptre & Harris, 1995, for discussion ofmethodological issues). For this reason, dung counts for smaller speciesshould only be used with caution for a first indication of relative abundance.

Equipment/personnel� 30m tape-measure or topofil (hip-chain)� steel tape-measure (1 mm gradations)� fluorescent vinyl marker tape and marker pens to mark distances, or

more permanent numbered aluminium discs, hammer and nails� team of four people

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Site selectionMost aspects of site selection are the same as those for transect surveys

(section 5.3.3.). However, new transects should be used for dung transects.These may be along newly cut trails or may simply be unmarked survey routesfollowing a compass bearing.

Procedurei) It is advisable for every study to begin with dung decay trials to deter-

mine the length of time dung piles remain on the forest floor (but see ii below).To do a decay rate trial, at least 50 fresh dung piles should be located and marked.For elephants, each pile should be visited once a week and its state of decay eval-uated according to the categories on Form 5.3. In north-east Gabon, an averagedecay rate for elephant dung was calculated at 2.4% per day, with individual dungpiles lasting from a few days to many weeks (Barnes & Jensen, 1987).

ii) Barnes et al. (1997) showed that decay times for elephant dung areinversely related to rainfall in the month of deposition, and dung densities areaffected by rainfall in the previous two months. However, this varies betweendifferent geographical areas (Nchanji & Plumptre, 2001). Therefore, unlessdetailed baseline studies have been done in a given country or region, furthersurveys are necessary to estimate decay rates and calculate dung density perelephant (see Form 5.3 notes on elephant dung decomposition states).

iii) The principles and procedures for dung surveys are similar to thoseexplained for transect surveys in the previous section (section 5.3.3).

iv) During dung surveys, one person should search the ground for dungpiles while the others maintain the compass route, measure the distancewalked, and cut a path. The searcher should advance slowly, scanning theground from side to side. This takes a lot of concentration, and a differentmember of the team should take over as searcher every 250m or so. It may beworth surveying shorter distances (subsamples of the main transect) moreslowly and carefully for the pellets of smaller species (e.g. duikers), at least forpresence/absence data.

v) For leopards and many other carnivores, cutting a transect throughthe forest will yield little information, and it may be best to survey along roadsand trails. Distances can be measured by routing on a GPS.

Recordingi) When a dung pile is detected, record the distance along the transect

(with the 30m tape or hip-chain), the perpendicular distance from the centre ofthe transect to the centre of the dung pile (with the steel tape-measure), thestate of decomposition of the boli (the individual spheres of dung), and thevegetation type at that location. See Fig. 5.1

ii) You can also record tracksencountered incidentally on thesame sheet (Form 5.3), puttingtrack measurements and other com-ments in the general observationscolumn.

Fig. 5.1: Dung countsTransect measures for pellet/pilecounts. Measure the perpendicular dis-tance from the centre of a duiker pelletpile to the transect (a). For elephants,piles may be more dispersed and needto be measured in two ways: i) pile clus-ters on one side of the transect shouldbe measured to the outer (b1) and inner(b2) limit, these added together and thendivided by two; and ii) for a dispersedpile on either side of the trail, measurethe outermost perpendicular distance oneither side (c1 & c2), then subtract thesetwo distances and divide by two (afterWhite & Edwards, 2000).

Data analysisi) Calculating the width of the survey transect is done as for sighting

transects (above), using the perpendicular distances from the trail to each piledetected (in the case of elephants, excluding E state bolus piles, Barnes &Jensen, 1987). The mathematical calculations used to assess the variable stripwidth are complex but can be done using the computer program DISTANCE(section 5.3.3.). If possible, a minimum of 100 dung piles should be recorded(Plumptre, 2000), and the absolute minimum for this method of analysis isgenerally taken to be 40.

ii) The area of the transect is calculated as length multiplied by width,and the density of droppings as the number of dung piles divided by area.

iii) Once dung density has been calculated, figures are required for defe-cation and decay rates. Unless you have been able to calculate a defecationrate, use a standard rate of 17 boli/day for elephants (based on Wing & Buss,1970). For duikers the situation is more problematic, because it is unlikely thatdefecation or decay rates will be transferable between different species, forestsor seasons, and few have been studied (Koster & Hart, 1988).

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Transect route

a

b2c1

b1

c2

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Short-cut method for elephant dung countsIn an effort to reduce the time needed for detailed surveys, Barnes

(1988) describes a short-cut method, whereby an observer follows a compassbearing without cutting a trail, and records the presence of all elephant dungpiles (decomposition states A to E). At the most basic level of analysis, the pro-portion of 500m sections along the transect which contain dung is fitted to acalibration curve established during more thorough research efforts, and thedropping density (piles/km2) read from the graph. The same data analysis pro-cedures as described above are then used to derive population estimates. Thisis a very coarse-grained method of estimating densities. However, as withreconnaissance surveys, the advantage is that a great distance can be coveredrelatively quickly. It provides distribution data and gives some indication of therelative importance of different areas for elephants in different seasons.

Fuller use has been made of field data (the recce method) in elephantsurveys in Gabon. Unlike in the full method described above, distance to eachdung pile was not measured, but estimates were made from the number ofpiles/km. This method is obviously less accurate, but it can cover about fourtimes more ground than the full method above (with the same effort). Walsh &White (1999) suggest using both methods, and calibrating different estimates.

B. Track (footprint) surveysFootprints or spoor (e.g. tracks of duikers, pug-marks of cats) give vital

information on the presence of species, including those that are rare or hard tospot, and can be carried out alongside other types of survey work. However,this method is less robust than dung counts for estimates of relative abundancebecause track densities are affected by the type and dampness of the soil sub-strate, rainfall, and the movement patterns of animals through the survey area.Also, track size and shape change with the animal’s gait, the soil substrate,and the age of the track. Fresh tracks in an ideal soil type have well-defined,vertical edges, making it relatively easy to measure them accurately, but mosttracks found will show some degree of spread as they fade. Edges becomesloped and poorly defined, making measurements difficult.

As a result of these variables, similar-sized species are hard to distin-guish from their tracks. Also, young animals leave tracks that resemble those ofadults from a smaller species (e.g. tracks of young red duiker resemble thoseof adult blue duiker). Some traditional hunters have been reported to be able todistinguish the tracks of all species (Koster & Hart, 1988), but, so far, biologistshave been unable to come up with objective methods to do this, and most tracksurveys lump forest antelopes together into two or three size categories.Species identification is less of a problem for cats since only the leopard andthe golden cat are present in forests, and they are very different in size.

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If it is possible to distinguish individual animals by their tracks, an esti-mate of population density can be made. Stander (1998) succeeded in doingthis for leopards in a semi-arid environment, with the assistance of experiencedSan hunters and the advantage of being able to survey large distances fromvehicles (he only found an average of one spoor each 38.1km). However, aswith distinguishing ungulate species, biologists have found it very difficult to pindown an objective methodology (see also Smallwood & Fitzhugh, 1993).

Equipment � ruler (marked in mm)� hand-rake� for tracing prints: sheets of acetate or glass and marker pens� for making casts of prints: plastic drinking straws, talcum powder,

plaster of Paris powder, mixing container, stirrer, paper casting frames,water, scalpel/sharp knife, and fine brush. Vinegar can also be used tomake casts set faster

Site selectionSite selection can be:i) Opportunistic – wherever tracks are seen.ii) Strategic – search any area where there is a damp, soft or sandy

damp substrate which will take an impression of a light footprint. Ideal placesinclude damp, sandy or dusty areas on roads and paths and sandy streambeds (in the dry season) or river banks.

iii) Systematic – set up track stations at regular intervals (e.g. every50–100m) along a transect. Clear all leaves and debris and rake the ground sothat it is smooth and soft enough to take animal footprints (e.g. Wilkie & Finn,1990).

Procedure and RecordingSite features and track details for different species/mammal groups

should be recorded on Form 5.4 (see White & Edwards, 2000, Chapter 10, formore detail). These measurements should be taken for up to three footprints ofthe same animal if possible. If unsure of the mammal group, make a sketchindicating scale and dimensions measured. Tracing onto acetate or glasssheets makes identification of individual cats from pug-marks easier (Panwar,1979).

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IdentificationThere are very few field guides that give details of footprint size and

dimensions for larger terrestrial mammals. Walker (1991) is a noteworthyexception, but covers mostly savannah mammals. Stuart & Stuart (1995, 1997)may be helpful for people working in East Africa, while the books byLiebenberg (2000), although restricted to southern Africa, may prove useful toanyone trying to master the art of identifying mammal or other spoor.

Fig 5.2: FootprintsThe basic footprint mea-

surements (in mm) are lengthand width – as shown on thefigures. For carnivores, lengthof pad and claws should be dis-tinguished, and for larger carni-vores the length and width ofthe large heel should be mea-sured (note if claws included).Length and width of toes canalso be taken.

Where possible, tracks ofcaptive animals should be mea-sured (e.g. in zoos) to get aclear idea of footprint shapesand sizes. One study ofantelopes in the West African

Table 5.1: Footprint lengths of species in West African forests

Max length (mm) Species

80–100 Bongo

50–75 Large duikers

(yellow-backed, Jentink’s, Abbot’s)

18–45 Bushbuck (30–45mm), medium/small,

duikers, chevrotain

Below 18 Dwarf antelopes (Neotragus spp.)

bottom: leopard & blue duiker, top: bushbuck& civet.

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forest zone (Newing, 1990), distinguished four, clear footprint size classes(Table 5.1). In addition to the species listed below, tracks of the sitatunga aredistinctive because of their very long, splayed hooves.

Taking permanent records of tracksWhen unusual tracks are found and cannot be identified immediately, it

is worth taking a record for identification back at base camp for future work.This can consist of a photograph, a tracing of a footprint, and/or a plaster ofParis cast.

The first step is to carefully clear any obvious debris obscuring the out-line of the print with tweezers, making sure the edges of the print are notaltered.

Photographing prints:i) Place a ruler next to the print for reference and photograph.ii) Record the film exposure number, species name, collection date,

location, identification number and collector’s name in a notebook.Tracing prints:

i) Place a glass plate over the print, ensuring the plate is flat, whichcan be done using adjustable screws as legs in the four corners ofthe plate.

ii) Trace the print outline, paying particular attention to its definition.iii) Record the species name, collection date, location, identification

number and collector’s name, either on the corner of the plate or in a notebook if the print is then to be traced onto paper.Casting Prints (in addition to photographs):

i) Using the straw, blow talcum powder over the print to prevent soil particles from sticking to the cast.

ii) Place a casting frame around the print (e.g. paper, cardboard, stiffplastic).

iii) Prepare the plaster of Paris – add water to the powder stirring con-tinuously until the mixture has a pancake batter texture.

iv) Slowly pour the mixture into the mould evenly, gently tapping to remove any air bubbles, which may distort the impression.

v) Engrave an identification number onto the cast before it solidifies.vi) Record the species name, collection date, location, identification

number and collector’s name in a notebook.vii) Leave casts to harden for approximately two hours (cover with

plastic if rain is imminent).viii) Remove casting frame and trim excessive edges, leaving a 10mm

border around the print.

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ix) Brush any loose debris from cast.x) Package in tissue or bubble wrap.xi) Store in a cool dry room.

Data analysisFor most species, analysis will be limited to presence/absence, or the

number of track sets and other signs recorded for each species per kilometrewalked. For large carnivores it may be possible to carry out multivariate analy-ses to identify individuals (e.g. Smallwood & Fitzhugh, 1993) if there are manymeasurements.

C. Photo-recordingPhoto-recording is expensive and requires patience to overcome mal-

functions of cameras, but it can be invaluable in recording the presence ofhard-to-detect species. Setting cameras with automatic trigger mechanismsallows low-labour monitoring of natural attractions (e.g. salt licks), baited sitesor commonly used thoroughfares. Camera-trapping can also be used to deter-mine activity patterns (nocturnal, diurnal, crepuscular), reactions to disturbance(e.g. Griffiths & van Schaik, 1993), seasonal movements and breeding pat-terns, and social structure. If enough cameras are used, it can also providesome information on abundance. Seydack (1984) gives a good example inSouth African forest, and Griffiths (1994) documents successful use in rainforestconditions for carnivores in south-east Asia. A full discussion of camera-trap-ping is beyond the scope of this manual. Interested readers should refer toKaranth & Nichols (1998) and Carbone et al. (2001).

Equipment� Photographic data-recording units, comprising: a) a camera with auto-

winder (or Polaroid camera), enclosed in weather-proof casing, andmounted on a stand; b) a flash system with casing; c) a trigger devicesuch as a trip-plate (300mm x 400mm), trip/bait wires, or a movementor heat sensor; and d) wires/other connectors between trigger andcamera.

� Passive cameras have either a trip-plate or a movement/heat sensor.A problem with movement sensors is that most types are triggered tooeasily (for example, by falling leaves or fruit). However, a laser sensoris available that can be set to send a beam at different pulses, andwhen the beam is broken for a certain length of time it activates thecamera; thus, the pulse rate can be set for a specific species.

� If a trip-plate is used, it is placed in a narrow place along a path. Whenan animal stands on it an electrical connection is made, causing the

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camera to expose a frame when the flash goes off, and the whole sys-tem automatically reloads for the next passing animal.

� If bait is being used to attract carnivores, then a mechanical triggerattached to the bait will set off the film and flash when tugged.

Site selectionThe camera needs to be facing a path, track or road along which mam-

mals commonly walk. A suitable position can be determined by finding animaltrails crossing paths and by the presence of dung, scrapes and tracks. It is alsoimportant to find places where the track is narrow, and animals pass near thecamera. A set of camera lines can be established to cover the whole surveyarea, or in the centre of several sampling units (e.g. Seydack, 1984). A suitablealternative is to use a baiting station and set the camera so that it will recordany animals that come to the station. This would be preferable in cases wheretrails get too much human activity, or to sample small carnivores and other ani-mals that do not habitually travel along roads/trails.

Procedure and Recordingi) Each camera is positioned at a strategic point and can be systemati-

cally rotated to maximise the area sampled. If a single camera is used, it canbe moved to different sites at intervals of a few days. Also record weather.

ii) Some trials are necessary to get the best pictures. Film speed, shutterspeed, aperture, distance from the plate, etc. all need to be adjusted to suitlocal conditions (e.g. Seydack, 1984).

iii) The majority of camera traps automatically record time and date uponactivation. If not, a board giving the camera number, location and date can beplaced within the field of the photograph, but without interfering with the sub-jects.

Data analysisi) The photographs are developed and the species identified, along with

age and sex where possible. For rare species this gives good information onpresence, and sometimes information on population structure. However, beprepared that the majority of photos will be of empty trails or individuals of alarge group of a single species, such as mangabeys. A lot of film will berequired to obtain a few photos of rare species.

ii) For species where individuals can be distinguished by markings (suchas coat patterns), photos from camera lines or cameras placed in samplingblocks can be used to count individuals, describe ranging patterns, andcalculate population densities. Plotting the number of new individuals caught onfilm against the cumulative photographic effort will give an indication of when

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the majority of individuals have been photographed in the sample area, and willenable you to use mark-recapture analysis techniques to estimate densities.

5.4 ConclusionsAll observations of animals or their signs should be recorded to build up

a broad picture of their distribution and abundance. For most species this is allthat rapid surveys can accomplish, especially where relatively few animals ortheir signs are encountered. However, relative abundance can be determinedmore accurately for elephants (with dung transect surveys) and duikers (with amixture of day and night transects and net drives). Long-term studies areessential for reliable population density estimates.

5.5 ReferencesArcher, A.L. (1994). A survey of hunting techniques and the results thereof on two species of duikerand the suni on Zanzibar Island. Unpublished report to Zanzibar Forestry Development Project.

Barnes, R.F.W. (1988). A Short-cut Method for Obtaining Preliminary Estimates of ElephantAbundance in Forests. IUCN/WCMC, Cambridge, UK. 9pp.

Barnes, R.F.W. (2001). How reliable are dung counts for estimating elephant numbers? Afr. J. Ecol.39: 1–9.

Barnes, R.F.W. & Jensen, K.L. (1987). How to Count Elephants in Forests. IUCN African Elephantand Rhino Specialist Group Technical Bulletin 1: 1–6. IUCN, Gland, Switzerland.

Barnes, R.F.W., Asamoah-Boateng, B., Naada Majam, J. & Agyei-Ohemeng, J. (1997). Rainfall andthe population dynamics of elephant dung-piles in the forests of southern Ghana. Afr. J. Ecol. 35:39–52.

Bell, R.H.V. (1984). The man–animal interface: an assessment of crop damage and wildlife control.In: Conservation and Wildlife Management in Africa, pp. 387–416. (Eds. R.H.V. Bell & E. McShane-Caluzi. US Peace Corps Training and Program Support.

Blum, L.G. & Escherich, P.C. (Eds.) (1979). Bobcat Research Conference Proceedings. NationalWildlife Federation Technical Report Series 6.

Bowland, A.E. (1990). The response of red duikers Cephalophus natalensis to drive counts.Koedoe 33(1): 47–53.

Buckland, S.T., Anderson, D.R., Burnham, K.P. & Laake, J.L. (1993). Distance Sampling:Estimating Abundance of Biological Populations. Chapman & Hall, London, UK.

Carbone, C., Christie, S., Conforti, K., Coulson, T., Franklin, N., Ginsberg, J.R., Griffiths, M.,Holden, J., Kawanishi, K., Kinnaird, M., Laidlaw, R., Lynam, A., Macdonald, D.W., Martyr, D.,McDougal, C., Nath, L., O’Brien, T., Seidensticker, J., Smith, D.J.L., Sunquist, M., Tilson, R. & WanShahruddin, W.N. (2001). The use of photographic rates to estimate densities of tigers and othercryptic mammals. Anim. Cons. 4: 75–79.

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Dorst, J. & Dandelot, P. (1983). A Field Guide to the Larger Mammals of Africa. Collins, London,UK.

Dubost, G. (1984). Comparison of diets of frugivorous ruminants of Gabon. J. Mammol. 65(2):298–316.

Estes, R.D. (1991). The Behavior Guide to African Mammals: including Hoofed Mammals,Carnivores, Primates. University of California Press, Berkeley and Los Angeles, California, USA.

Feer, F. (1989). Comparaison des régimes alimentaires de Cephalophus callipygus et C.dorsalis,bovidés sympatriques de la forêt sempervirente africaine. Mammalia 53(4): 563–604.

Griffiths, M. (1994). Population density of Sumatran tigers in Gunung Leuser National Park. In:Sumatran Tiger population and Habitat Viability Analysis Report. (Eds. R. Tilson, K. Soemarna, W.Ramono, S. Lusli, K. Traylor-Holzer & U. Seal). Indonesian Directorate of Forest Protection andNature Conservation and IUCN/SSC Conservation Breeding Specialist Group. Apple Valley,Minnesota, USA.

Griffiths, M. & van Schaik, C.P. (1993). The impact of human traffic on the abundance and activityperiods of Sumatran rain forest wildlife. Conserv. Biol. 7: 623–626.

Haltenorth, T. & Diller, H. (1984). A Field Guide to the Mammals of Africa, Including Madagascar.Collins, London, UK.

Hill, C.M. (1998). Conflicting attitudes towards elephants around the Budongo Forest Reserve,Uganda. Environm. Conserv. 25: 244–250.

Hill, C.M. (2000). Conflict of interest between people and baboons: crop raiding in Uganda. Int. J.Primatol. 21(2): 299–315.

Karanth, K.U. & Nichols, J.D. (1998). Estimation of tiger densities in India using photographic cap-tures and recaptures. Ecology 79: 2852–2862.

Kingdon, J. (1997). The Kingdon Field Guide to African Mammals. Academic Press, London, UK.

Koster, S.H. & Hart, J.A. (1988). Methods of estimating ungulate populations in tropical forests. Afr.J. Ecol. 26: 117–126.

Lahm, S.A., Barnes, R.F.W., Beardsley, K. & Cervinka, P. (1998). A method for censusing thegreater white-nosed monkey in north-eastern Gabon using the population density gradient in rela-tion to roads. J. Trop. Ecol. 14: 629–643.

Liebenberg, L. (2000). Photographic Guide to Tracks and Tracking in Southern Africa. NewHolland, South Africa.

Muchaal, P.K & Ngandjui, G. (1999). Impact of village hunting on wildlife populations in the westernDja Reserve, Cameroon. Conserv. Biol. 13: 385–396.

Naughton, L., Rose, R. & Treves, A. (1999). The social dimensions of human–elephant conflict inAfrica: A literature review and case studies from Uganda and Cameroon. Report to IUCN AfricanElephant Specialist Group, Human Elephant Task Force. Gland, Switzerland.

Nchanji, A.C. & Plumptre, A.J. (2001). Seasonality in elephant dung decay and implications for cen-susing and population monitoring in south-western Cameroon. Afr. J. Ecol. 39: 24–32.

Newing, H.S. (1990). Distinguishing antelope dung and tracks - a zoo study of Upper Guinean for-est species, West Africa. Unpublished report.

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Newing, H.S. (1994). Behavioural ecology of duikers (Cephalophus spp.) in forest and secondarygrowth, Taï, Côte d’Ivoire. PhD Thesis, University of Stirling, Scotland.

Noss, A.J. (1999). Censusing rainforest game species with communal net hunts. Afr. J. Ecol. 37(1):1–11.

Nummelin, M. (1990). Relative habitat use of duikers, bush pigs, and elephants in virgin and selec-tively logged areas of the Kibale Forest, Uganda. Trop. Zool. 3: 111–120.

Panwar, H.S. (1979). A note on tiger census technique based on pugmark tracings. Tigerpaper 6:16–18.

Peres, C. (1999). General guidelines for standardising line transect surveys of tropical forest pri-mates. Neotropical Primates 7(1): 11–16.

Plumptre, A.J. (2000). Monitoring mammal populations with line transect techniques in Africanforests. J. Appl. Ecol. 37: 356–368.

Plumptre, A.J. & Harris, S. (1995). Estimating the biomass of large mammalian herbivores in atropical montane forest: a method of faecal counting that avoids assuming a steady state system.J. Appl. Ecol. 32: 111–120.

Rosevear, D.R. (1974). The Carnivores of West Africa. Trustees of the British Museum (Nat. Hist.),London, UK.

Seydack, A.H.W. (1984). Application of a photo-recording device in the census of larger rain-forestmammals. S. Afr. J. Wildl. Res. 14: 10–14.

Smallwood, K.S. & Fitzhugh, E.L. (1993). A rigorous technique for identifying individual mountainlions Felis concolor by their tracks. Biol. Cons. 65(1): 51–59.

Stander, P.E. (1998). Spoor counts as indices of large carnivore populations: the relationshipbetween spoor frequency, sampling effort and true density. J. Appl. Ecol. 35: 378–385.

Stuart, C. & Stuart, T. (1995). Southern, Central and East African Mammals. Struik Publishers,Cape Town, South Africa.

Stuart, C. & Stuart, T. (1997). Field Guide to the Larger Mammals of Africa. Struik Publishers, CapeTown, South Africa.

Walker, C. (1991). Signs of the Wild: Field Guide to the Spoor and Signs of the Mammals ofSouthern Africa. Struik, Cape Town, South Africa.

Walsh, P.D. & White, L.J.T. (1999). What it will take to monitor forest elephant populations.Conserv. Biol. 13(5): 1194–1202.

White, L.J.T. (1995). Factors affecting the duration of elephant dung piles in rain forest in the LopeReserve, Gabon. Afr. J. Ecol. 33: 142–150.

White, L. & Edwards, A. (Eds.) (2000). Conservation Research in the African Rain Forests: ATechnical Handbook. Wildlife Conservation Society, New York, USA.

Wilkie, D.S. & Finn, J.T. (1990). Slash-burn cultivation and mammal abundance in the Ituri Forest,Zaïre. Biotropica 22(1): 90–99.

Wilson, V. (1990). Duiker Survey in Central African Republic. Chipangali Wildlife Trust, Zimbabwe.

Wing, L.D. & Buss, I.O. (1970). Elephants and forests. Wildl. Monogr. 19: 1–92.

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Form 5.1: Recording Sheet for Sightings from

Observation Points

Surveyor:

Address:

Date:

Field sheet ref:

(total observers)(dd/m

m/yy)

Survey site:

Observation point:

Vegetation:

Latitude:Longitude:

UT

M (if available):

Altitude:

Weather:

Tim

e at start of watch:

Tim

e at end of watch:

Other:

Start tim

eS

peciesN

o. of animals

Additional observations (behaviour, food eaten etc.)

End tim

e ofof obs.

observationM

ale/ Sub Juv/

Fem

ale adults inf

96

Form

5.2

: Rec

ordi

ng S

heet

for

Sig

htin

g Tr

anse

cts

Sur

veyo

r:A

ddre

ss:

Dat

e:F

ield

she

et r

ef:

(tot

al o

bser

vers

)(d

d/m

m/y

y)

Sur

vey

site

:V

eget

atio

n:W

eath

er:

Latit

ude:

Long

itude

:U

TM

(if

avai

labl

e):

Alti

tude

:

Tra

nsec

t le

ngth

:S

tart

tim

e:E

nd t

ime:

Oth

er:

Tim

eD

ista

nce

Veg

e-S

peci

esN

o. o

f an

imal

sC

ueP

erpe

n-G

roup

A

dditi

onal

obs

erva

tions

alon

gta

tion

dicu

lar

spre

adtr

anse

ct

dist

ance

Mal

e/

Sub

-

Juv

/Fe

mal

ead

ult

in

f

Cue

– H

(he

ard)

or

S (

seen

)

P

erpe

ndic

ular

dis

tanc

e =

dis

tanc

e fr

om n

eare

st p

oint

on

tran

sect

to

posi

tion

at w

hich

ani

mal

was

firs

t de

tect

ed (

in m

etre

s)G

roup

spr

ead

= s

prea

d of

gro

up o

f ani

mal

s of

a s

ingl

e sp

ecie

s, r

ecor

ded

in a

sin

gle

sigh

ting

(in m

etre

s)

Obs

erva

tions

= b

ehav

iour

, ass

ocia

tion

with

oth

ersp

ecie

s; a

ny o

ther

com

men

ts

97

Form 5.3: Recording Sheet for D

ung Transects

Surveyor:

Address:

Date:

Field sheet ref:

(total observers)(dd/m

m/yy)

Survey site:

Vegetation:

Weather:

Latitude:Longitude:

UT

M (if available):

Altitude:

Transect length:

Start tim

e:E

nd time:

Other:

Distance

Species

T/D

Bolus. state

Distance from

Vegetation type and general observations (including descrip-

(km)

& diam

.transect (cm

)tion and m

ax. width and length (m

m) for tracks)

Notes: D

istance from start =

from start of transect; T

/D =

tracks/dung; Bolus state: A

– fresh, whole, m

oist and smelly; B

= fresh, w

hole and odourless; C1 =

> 50%

boli intact;C

2 = <

50% boli intact; D

= form

less, flat mass; E

= D

ecayed to a stage that it cannot be detected at a range of two m

etres, and would not be seen on a transect unless under-

foot (adapted from B

arnes & Jensen, 1987) M

ake measurem

ents of the diameter of intact elephant boli (in cm

)

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Form 5.4: Recording Sheet for Tracks

Surveyor: Date: Field sheet ref:(total observers): (dd/mm/yy)

Address:

Survey site: Vegetation: Weather:

Latitude: Longitude: Altitude:

Transect length: Start time: End time:

Other:

Location Species Soil Soil Vegeta- Clarity of Measurements(transect type mois- tion type print (mm)marker turenumber)

Soil type: S = mostly sandy; C = mostly clay; St = stones; Si = mostly silt.Use combinations where necessary, e.g. C+St = mostly clay + stonesSoil moisture: dry; damp; wetClarity of print: distinct = well-defined with clear edges; fair = mostly well-defined but someedges ‘spread’ or confused by other tracks or debris; indistinct = clear enough for identifica-tion but measurement difficult because of spread, other tracks or debris.

6.1 BiologyAfrican primates are divided into three taxonomic groups (Oates, 1996):

the small, nocturnal prosimians (20+ species); the monkeys (45+ species); andthe apes (3+species). Likehumans, non-human primatesthat are active inthe daytime gener-ally have a poorsense of smell,moderate hearingand excellent eye-sight (nocturnalspecies are obvi-ously very different,having weak dis-tance-vision andacute hearing).Savannah species(e.g. baboons) andthe lemurs ofMadagascar are notdiscussed in thischapter, but the for-est survey proce-dures still apply tothese specieswhere they dooccur in forests.

Prosimians These primitive primates are separated into two families: the galagos

(Galagonidae) and the lorisids (Loridae). All species are primarily nocturnal(Charles-Dominique, 1977). Forest galagos are generally small (18+ species;50–300g), although three species exceed 1,500g in weight. They live in smallfamily units, travelling and foraging in the understorey and middle canopy of

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6. PrimatesGlyn Davies

mon

a m

onke

y (C

erco

pith

ecus

mon

a)

100

the forest, and make distinctive calls between group members to maintain con-tact. Loud calls are made when alarmed, and to signal to other groups/individ-uals. Recent taxonomic work has shown how these calls are important in dis-tinguishing different species (Bearder et al., 1995).

The potto (genus Perodicticus) and two angwantibo species (genusArctocebus) are larger (400g–1,500g), mostly solitary, and move slowly alongbranches or through liana tangles, often in the middle and upper canopies ofthe forest. Angwantibos will also use shrubby undergrowth in clearings. Whennot in direct contact, they communicate by scent-marking twigs and branches,and do not make loud calls.

GuenonsForest guenons (genera Cercopithecus, Miopithecus and Allenopithecus)

are relatively small-bodied monkeys (1–8+kg), which live in groups of about10–30 individuals occupying stable home ranges that generally cover20–100ha (Gautier-Hion et al., 1988). All species can be distinguished on thebasis of their species-specific facial colour patterns, and the loud calls given bythe adult males. Calls are made at various times during the day, especiallyearly morning and late afternoon, and when one group calls this often sets off asequence of calls and replies between neighbouring groups.

Many guenons have species’ ranges with a wide altitudinal distributionand habitat use. Exceptions to this generalisation are: the l’Hoest/Preussspecies group, most of which do not occur in the lowlands (excluding the sun-tailed monkey, C. solatus, in the lowlands of Gabon), and species which con-centrate in riverine/swamp forest environments (e.g. Allen’s swamp monkey,talapoins), or in forest-edge vegetation (e.g. Sykes monkeys).

Most breeding groups have a single adult male, several adult femalesand young. Young adult males tend to leave the group of their birth and travelsubstantial distances, sometimes in the company of other adult males,sometimes as lone males.

Colobus monkeysThere are three taxonomic groups of colobus monkeys: olive (one

species), red (14+ species/subspecies) and black-and-white (five species)(Davies & Oates, 1997).

The black-and-white colobus species (9.5–13kg) generally live in smallgroups (c. 5–15) and occupy small home ranges (20–50ha). Each group hasone, or sometimes two, adult males that engage in daily choruses of territorialloud calls, often pre-dawn and in the early morning. Despite this noisy behav-iour, however, they tend to remain silent and hide when alarmed by humans.Two exceptions to this ecological model are Angolan pied colobus (Colobus

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angolensis) in Ituri (Zaire) and Nyungwe (Rwanda) and Black colobus (C.satanus) in Forêt des Abeilles (Gabon), which live in much larger groups(sometimes hundreds of animals) in larger home ranges (not territories).

Red colobus (8.5–10kg) adult males lack loud calls, but can be detectedfrom their occasional noisy chatter and alarm calls on seeing humans. Redcolobus (Procolobus spp) live in groups of 10–50 individuals (sometimes evenlarger) occupying home ranges of 50–100ha that are not defended as territo-ries; there is considerable overlap between neighbouring groups. The diminu-tive olive colobus monkeys, Procolobus verus, (4kg) are very secretive, live insmall groups with one or sometimes two adult males, have a quiet, shrill call,and often travel in the company of other monkey groups. They are difficult todetect.

Mangabeys, mandrills and drills The mangabeys (females: 6kg; males: 10kg), and drills/mandrills

(10–20kg) are large-bodied and live in large groups (drills up to 100;mangabeys: 15–30+) that travel rapidly over wide areas of forest, often splittinginto smaller groups when foraging. Groups contain several adult males thatmake loud calls which may be audible from distances greater than 1km, as wellas the noisy squabbles within groups which indicate a group’s presence within100m or so. In rare instances, mandrills, Mandrillus sphinx, have been record-ed forming hordes of over 500 animals, reflecting a dynamic social system thatcan be maintained in large tracts of forest. Most time is spent travelling andforaging on the forest floor, often noisily searching leaf-litter for insects and fall-en fruits, but they also feed and sleep in large trees. Grey-cheekedmangabeys, Lophocebus albigena, are exceptional in being largely arborealthroughout the day.

ApesThere are four ape species: chimpanzee, Pan troglodytes, (30–40kg),

gracile (or bonobo or pygmy) chimpanzee, Pan paniscus (25–35kg), and twospecies of gorilla (90–200kg), the western lowland gorilla, Gorilla gorilla, andthe mountain gorilla, G. beringei; all are large-bodied and travel long distancesalong the ground (McGrew et al., 1998).

Chimpanzees live in fission-fusion communities, so group sizes varyfrom small units comprising a mother and offspring to large congregations inexcess of 20 individuals around large food sources (e.g. fruiting fig trees). Theyare very vocal, making noisy displays with hoots, shouts and drumming on treebuttresses, all of which aid detection during surveys. Bonobos have a societythat is more cohesive and influenced by strong female-female bonds. They arerestricted to low-lying forest formations in the Congo Basin south of the Congo

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River. Gorillas live in stable family groups of 5–30 animals, with a single, orsometimes two fully adult males. They are less noisy than chimps, but malesdo have clearly audible chest-beating displays.

All four ape species leave hindfoot and front knuckle prints when theytravel over damp/soft ground, make nests to sleep in each night (chimps andbonobos in trees but sometimes on the ground, gorillas in the understorey andmiddlestorey and on the ground), and produce large, long-lasting characteristi-cally shaped faeces at sleeping and feeding sites. These signs are commonlyused during surveys, supplemented with evidence from areas damaged duringfeeding and play, and records of sightings, loud calls, tree drumming, andchest-beating.

6.2 Management issuesPrimates are important components of forest ecosystems: gorillas can

have a major impact on plant regeneration; guenons pollinate flowers and dis-perse seeds; colobus monkeys commonly destroy seeds; and the combinednumbers of all primates account for the bulk of medium-sized mammalian bio-mass in many forests. Their unseen and often unrecorded influence on ecosys-tem function is an important consideration for forest managers. Moreover, theloss of forest habitat is a key reason for primate species extinctions (e.g.Cowlishaw, 1999; Oates et al., 2000).

Probably the most important use of forest primates is exploitative: hunt-ing and trapping for food – or bushmeat. Bushmeat is important in rural com-munities both in terms of subsistence consumption, providing much neededanimal protein, and for trading activities. In West and Central Africa, where eco-nomic hardship has resulted in greater dependence on forest products, therehas been a marked increase in commercial exploitation of primates in recentyears. Large tracts of forest have been heavily hunted to supply primates, andother species, to ever demanding urban centres. Hunting and trapping of pri-mates is less common in the drier southern and eastern African regions wherecattle do relatively well and consumption of primate meat is often disdained onreligious or cultural grounds; however, it does still occur.

Larger species tend to be the main target of the bushmeat trade,because these animals supply more food for each cartridge spent, and tradi-tional taboos on hunting apes are increasingly being ignored, with the resultthat these large-bodied animals are now used in trade. Smaller species aretaken when encountered, and when larger species have been eliminated. Inaddition to hunting for food, some primates are consumed for other reasonsthat can have significant localised impacts. These include: providing ceremonialskins (e.g. black-and-white colobus); selling trinkets for the tourist trade (e.g.

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gorilla hands); supplying animals for the pet trade; supplying biomedicalresearch centres (e.g. chimpanzees). All these activities obviously lead todeclines in the target species.

The size of forest primates is a less useful factor for predicting timberextraction impacts. For all forest species, there is a risk that as forest habitat isaltered it will become less suitable, thereby eliminating the least adaptablespecies first. Gathering of forest products has long affected forests throughoutAfrica, and primates have continued to survive, but the scale and rate of recentcommercial timber extraction has radically altered forest quality. A recentreview of the effects of logging on primates (Plumptre & Johns, 2001) indicatesthat very few African primates are actually lost as a result of habitat changesfollowing logging, with red colobus at some sites being an exception (e.g.Skorupa, 1986). However, long-term effects of vegetation changes are hard topredict (e.g. Chapman et al., 2000), and improved access for hunters and trap-pers along logging roads is a major secondary impact of logging.

A common problem that arises at the forest-farm boundary is that of cropraiding by primates which refuge in the forest; this is a major managementissue. Guenons and mangabeys are common pests of cash and food crops,and even galagos are considered as pests of cashew nuts on the Kenya coast.Chimpanzees and gorillas are keen on bananas and plantains and can do sub-stantial damage in a short time to these flimsy plants. The consequence is thatfarmers kill the primates in order to protect their crops, which has resulted inlosses of even protected species such as gorillas on the periphery of theBwindi Impenetrable National Park in Uganda.

A positive attribute of primates is that tourists find them attractive andinteresting. In areas with a large number of primate species, ideally at highpopulation densities, there is ample scope for ecotourism development, evenwhere thick forest vegetation hampers viewing. In Uganda, this has beendeveloped for the two largest, and most tourist-attractive, species: the chim-panzee and the gorilla. In all cases, the animals have been habituated tohuman visits, and this usually takes a long time. There is an associated riskthat animals that lose their wariness of humans become easy targets forhunters, or become pests around farms, villages and tourist hotels. They alsobecome vulnerable to contracting human diseases from visiting tourists(Butynski & Kalina, 1998).

Ecotourism and the maintenance of primate populations are obviouscomplementary activities. In this context, the IUCN conservation action plan forAfrican primates (Oates, 1996) makes the point that dry forest and savannahzone primates in Africa have wide distributions and occur in many protectedareas, whereas the populations of the majority of primates from the six lowlandforest and four upland/highland forest communities are under much greater

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threat. Surveys of the distribution and abundance of primates are thereforeneeded to guide conservation planning and action, as well as obtain facts toinform forest management.

6.3 Methods

GeneralSurvey methods for primates have been thoroughly reviewed in a 1981

publication by a subcommittee of the US National Research Council (NRC,1981) on the Conservation of Natural Populations, to which reference shouldbe made. The interpretation of survey field data relies on an understanding ofprimates’ reproductive biology, ecology and behaviour, which has been collect-ed from long-term studies of primates. Examples of long-term study sites inAfrica include: Kibale and Budongo in Uganda; Tana River and Kakamega inKenya; Gombe and Mahale Mountains in Tanzania; Virunga Volcanoes inRwanda; Tiwai Island in Sierra Leone; Taï in Côte d’Ivoire; and Makokou andLopé in Gabon. Information from these and other sites should be consultedbefore embarking on a survey.

Selecting a survey method involves a compromise between time/person-nel available and the information needed for management planning. It is there-fore important to write down clearly what questions the survey is to answer,and then decide if there are sufficient resources to gather this information.Before making a final decision on which methods to choose, a quick walkthrough an area is important to make a general assessment of the populationsto be surveyed, and identify future transect survey sites.

IdentificationThe use of field guides, such as those discussed in section 5.3 for large

mammals, should be supplemented with information on the colour of animals,based on examination of skin collections in museums, on live specimens inzoos, and on an appreciation of the vocal repertoire of different species. Thereare few primate call sound libraries, so it is helpful to visit an existing studyarea where primate calls can be learned. Such visits also provide an opportuni-ty to make inquiries about local names and develop a general understandingabout species’ ecology, abundance and interaction with human populations.The survey team’s ability to identify primate species correctly is central toobtaining useful results; time spent in training will pay good dividends duringsurveys.

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6.3.1 Distribution surveysOne of the first things that should be determined is what primate species

occur in the area. This can be done by checking a range of sources, includingrecords from the literature and museum specimens, and by spending time withlocal farmers and hunters, as well as with forest, wildlife, national parks andother government officers. The interview information needs to be verified care-fully (see section 2.6), and then recorded onto standard checklists (Form 6.1),which can then be computerised and marked onto maps.

The information on distribution maps, which show where differentspecies occur, or have occurred in the past, can be presented on a range ofscales from local to global. To facilitate transposing information from one scaleto the next, it is important to use a standard mapping unit from the outset, suchas degrees (or quarter degrees) of latitude and longitude or the UTM globalmetric grid. This allows countrywide maps to be drawn, onto which changes inspecies distribution can be mapped over time (see Fig. 6.1).

At the local level, an accurate (1: 50 000 scale) topographical map isneeded, supported with recent aerial or satellite photographs if available.These should be used to assess information on vegetation and altitude, andproximity of villages, roads, urban centres, etc. Thereafter, visits can be madeto different areas, and by mapping all reliable sightings and other records apreliminary assessment can be made of which areas are suitable for primates.This information is very important to guide forest management, but it is insuffi-cient to estimate population densities.

Fig. 6.1: Distribution of four primate species in Sierra Leone (Grubb et al., 1998)

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6.3.2 Line transectsLine transect methods for surveying vertebrate populations (review in

Buckland et al., 1993) have been adapted for forest primate surveys (seereviews: NRC, 1981; Whitesides et al., 1988; Peres, 1999; Plumptre, 2000).The main aim of these surveys is to determine the population density of pri-mates in the area and to ascertain what factors play a role in affecting theirnumbers.

Equipment/personnelThe details of general survey equipment, personnel and site selection

have been elaborated in the previous chapter (section 5.3.3). The same princi-ples should be applied for primates, although direct surveys of mobile, group-dwelling species present their own problems that will be discussed in the sec-tion on data analysis.

Site selectioni) On an accurate map, select the places where transects should begin,

and the direction in which they should run. This can be done using randomnumber tables to select transect start points and bearings. Alternatively, tran-sects can be laid out to sample particular areas of interest on a stratified sam-pling basis depending on the area and spread of forest habitats. Transects canbe cut to point in different directions and should be at least 1km apart at allpoints, to gain an idea of population densities over a wide (and therefore repre-sentative) area (see section 5.3.3. for further discussion). Straight line transectsshould be cut through the forest, following a compass bearing.

ii) Local hunters and guides can help in locating suitable campsites andtransect start points. As noted for ungulates, transects should not begin tooclose to the camp noises and smells (over 300m away).

iii)The use of established roads, tracks and paths greatly reduces thetime spent in establishing a survey transect. However, this tends to introduceserious bias to the survey, because: a) the roadside vegetation differs signifi-cantly from the rest of the forest, and/or b) primates change their behaviour inrelation to the road, track or path (e.g. if hunters commonly use them).

iv)Once the transects have been cut, ensure that the survey area has adistinctive name, and that each transect is clearly distinguished from the othersby a unique number. After cutting the transect, wait at least 24 hours beforeproceeding with the survey so that primates can recover from the disturbanceto the area.

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A. Animal sightings

Procedurei) Early in the morning (soon after dawn) or in the afternoon (after about

15:00), a surveyor (or small group of surveyors) should walk slowly and quietlyalong the transect. For example, Butynski (1984) walked at less than 1km/hr,stopping every 60m for 30–60 seconds to look around and listen, and others(e.g. Peres, 1999) have described similar speeds of 1.25km/hr.

ii) Transects should not be crossed by other survey teams during thesurvey period, since this will disturb groups which may leave the area to besurveyed.

iii)The ability to detect primates may be affected by the weather: somespecies call less on windy days and all are more difficult to see in windy andrainy conditions. As a result, it is important to avoid surveys during rain, andimmediately afterwards, when the sound of dripping water obscures othersounds.

iv)Other factors affecting survey results include: a) time of day –primates tend to be more active in the early morning and late afternoon;b) human activities – primates call less and are more wary in areas wherethere is hunting; and c) the experience of the observer. These parameters allneed to be recorded (see top section of Form 6.1).

Recordingi) At the first encounter with a primate, the means of ‘detection’ (sighting,

branch movement, falling fruit, alarm calls, fleeing animals, etc.) should benoted immediately, and the recording sheet filled out as fully as possible (Form6.1). It is very important to make accurate measurements of the distance fromthe transect to all individuals that are seen (see Fig. 6.2). The perpendiculardistance from the transect to each primate should be determined by directmeasurement, using a tape measure, marked (non-stretch ropes), or optical (orlaser) range-finder. As mentioned in section 2.5, estimating distance by eye isfraught with inaccuracy and variability between observers, and, over time, thecalculation of perpendicular distance from the observer to animal and the angleof sighting introduces two potential sources of error.

ii) It is often useful to put a field bag on the transect at the point fromwhich the first animal was seen, as a reference point from which other mea-surements can be made. The places where animals were first seen need to beclearly recognised, and the transect marker nearest the observer should berecorded.

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Fig. 6.2: Line transectiii) Information should be gath-

ered about the primate group itself,including: how many different individu-als were seen (adult males, females,infants, any special marks like benttails, etc.); estimated group size(including those heard but not seen);the area over which sighted animalsare spread, as well as the overallgroup spread. Time should be allowedto move up and down the transect,and left and right, to gather this infor-mation, although it is important not tomove away from the transect for morethan 10 minutes.

iv) Other behavioural details to record include: what the group was doingwhen encountered (if feeding, what were the animals feeding on); the group’sreaction upon seeing the observer (e.g. wary curiosity, panicked flight, indiffer-ence, etc.); at what height, and in what type of vegetation, they were found.

Data analysisTo calculate the population density in groups/km2, three sets of data are

required: i) The length of transect surveyed, which is determined by multiplying the

length of the transect by the number of times it was surveyed.ii) The number of groups encountered, which should include all those

groups containing both males and females, with a separate note of groupswhich appeared to contain only adult males; solitary animals should also benoted separately.

Using these two pieces of information the relative abundance of aspecies (e.g. groups per kilometre walked) can be calculated. This was done inKibale, where Skorupa (1986) provided statistically robust data that showed dif-ferences in primate numbers between logged and unlogged forests. But thiscan only be done if it is possible to determine differences in the probability ofdetecting primates at either site (Skorupa, 1987).

iii) The width of the survey strip multiplied by the distance surveyed willgive an area of forest in which a certain number of primate groups were record-ed; this, in turn, provides an indication of population density (groups/unit area).However, the detectability of groups on either side of the transect line is notfixed, i.e. it is not possible to say that all groups within 40m on either side of thetransect will be seen, and all those more than 40m away will not be seen.

monkeygroup

observer/animaldistance

perpendiculardistance

Transectroute

sightingangle

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The transect width is influenced by: a) the detectability of the species(e.g. shy versus conspicuous behaviour); b) vegetation type; c) terrain; and d)the spread of a group (Whitesides et al., 1988). All these parameters can varybetween sites, seasons and species, and to be able to estimate the transectwidth it is necessary to gather enough information on species-specific andhabitat-specific observer–animal sighting distances (preferably 40–100 inde-pendent field records for each species at each survey site). With these data,the effective strip width for sighted individuals can be calculated using theDISTANCE programme (Buckland et al., 1993; see section 5.3.3).

A complicating factor in judging the width of a transect is the groupspread (the area occupied by a group of monkeys). This will influence howmany monkeys you see at a given group encounter, since the presence of onegroup affects the locality of other groups, as well as the concentration of mon-keys within an area (Fig. 6.3). Some surveyors have tried to address this prob-lem by estimating average group spread for each species (from long-term stud-ies), and adjusting transect width estimates accordingly to the anticipated cen-tre of the group from the transect (Whitesides et al., 1988). However, othersadvise against this approach, emphasising that it is necessary to use onlysighting data for all individuals seen (Plumptre, 2000), and calculating thecentre of the group spread from the centre of the sightings.

perpendicular distance from the transect (m)

10 20 30 40 50 60 70 80 90 100

Fig. 6.3The cumulative number ofsightings of groups of twospecies of primates:spot-nosed monkey [s],Cercopithecus petaurista,and Diana monkey [d],Cercopithecus diana, withincreasing distance oneither side of the transect.The two triangles show thedistance from the transectwithin which 80% of allgroup sightings were made(adapted from Whitesideset al., 1988). s d

100

80

60

40

20

cum

ulat

ive

num

ber

of g

roup

sig

htin

gs (

%)

Advantages/limitationsi) Given the poor visibility in forest conditions, and the short time over

which surveys are conducted, obtaining detailed estimates of population densi-ties is very difficult. However, clear estimates of the relative abundance of pri-mates at different sites is often adequate for management purposes (for exam-ple, knowing that there are more primates of species X in forest A than in forestB). Certainly it can give a clear indication of areas that need special manage-ment attention.

ii) The use of DISTANCE software to analyse survey results is based ona number of basic assumptions (see section 5.3.3). Some of these factors areoutside the control of the observer, but the quality of field records is greatlyimproved if time is taken to develop an understanding of the primates beingsurveyed, and to do practice surveys (Peres, 1999).

iii)The number of times that surveys must be repeated depends uponthe length of the transect and the number of encounters per kilometre. As arough guide, 100 records were determined as a minimum sample size forrobust statistical analysis in Budongo forest (Uganda), which required over 200km of surveys (Plumptre, 2000). Smaller sample sizes can be used, but statisti-cal confidence limits associated with density estimates need to be shownclearly.

iv)The line transect survey method can be used by a single observer (orsmall survey team), which is a major advantage when manpower constraintslimit survey work. However, the observer needs to be experienced with speciesbehaviour for this method to be effective.

B. Nest countsThe nests that are made by gorillas and chimpanzees, both for sleeping

at night and also for resting during the day, persist on the ground or in treeswell after they were first made. These conspicuous signs of species’ presence,which generally occur at low population densities, have long been used in sur-veys (e.g. Tutin & Fernandez, 1983). The same principles described for indi-rect surveys of ungulate signs along transects and recce tracks can be applied(section 5.3.4), and are described in more detail by White & Edwards (2000) –using Form 6.2.

As with dung surveys, the critical information needed to translate countsof nests/km surveyed are: the rate at which nests are made/individual (takingaccount of age differences), and the rate at which nests disintegrate until theyare hardly discernible any longer (which will vary with season, altitude, speciesand so on). At sites where there are many nests, the need to calculate decayrates can be avoided by doing repeat surveys (e.g. every one to three months)and marking all nests seen on a map (or with flagging tape) – see

110

111

section 5.3.4A. It is then possible to record the number of new nests producedin a given period of time, within a known survey area (km2), and then to converta nest density figure into an estimate of individuals/km2 using a calibration forthe number of nests made per day by different types of animals (males,females, etc).

A number of studies have been carried out to look at these problems indifferent African forests, and they should be referred to for more details(Hashimoto, 1995; Tutin et al., 1995; Plumptre & Reynolds, 1997; Hall et al.,1998; Blom et al., 2001).

In summary, the analysis of the results depends on the amount of back-ground information available for the survey area during the season when thesurveys were carried out. If there is good evidence that the nests are from aparticular species, then species distribution maps can be drawn up. As informa-tion on nest building and decay rates is determined (by site and season), so itwill become possible to give reasonable estimates of gorilla and/or chimpanzeepopulations’ decay rates (which are often variable).

C. Mapping callsLoud calls can be used to detect groups from greater distances than is

possible with sightings. In areas where species are very vocal this provides auseful survey method, but even quieter chatters and squeals, and movementsin the branches, can be used to detect primates over shorter distances. Seealso sections 3.3.10 and 7.3.9.

Equipment/personnel� map-making equipment: 360o protractor, graph paper, ruler, pencils,

etc.� high-quality portable tape recorder or mini-disc player, microphone

and batteries, blank tapes or mini-discs (to record unidentified andunusual calls, or to analyse calls and compare calls between areasand seasons)

� recorded tapes/CDs for playback experiments (to get resident groups to call)

� plastic bag or like for protecting equipment against moisture� surveyors with good knowledge of primate calls

Procedurei) For diurnal species, the surveyor should start early (just before dawn

for many species) and walk slowly (1km/hr) and wait at marked points to listenfor calls. On hearing a call the surveyor should wait for between 15 and 30minutes until the calling group, and any that are replying, seem to have

112

stopped. For nocturnal species, the start time of the survey should obviouslychange: galagos commonly give loud calls around dusk and during the hour orso before dawn.

ii) The survey should be repeated for a number of days, depending onthe species, site, season and weather conditions. For vocal species (e.g. black-and-white colobus), as little as three days may be sufficient to record all callinggroups in the survey area, but longer survey periods will be needed at siteswhere fewer or quieter calls are made. In general, surveys need to continueuntil the number of groups mapped in a given area becomes consistent.

RecordingOn hearing a call, the following information must be collected (using

Form 6.3, or a separate sheet for calls): date, time, weather, etc.; species;detection (type of call); bearing (of the call from the surveyor); observer–animal(estimated distance to calling animal); map (the trail marker from where the callwas heard). Whenever the same group calls again, after the surveyor hasmoved to a new position, new bearings should be taken again so that thegroup’s position can be mapped more accurately through triangulation.

Data analysisi) An accurate map of the survey area should be drawn (useful scale is

10mm: 100m) onto graph paper, including key topographical features (e.g.streams, ridge tops, etc). Copies of the master map should then be made formapping each species separately (Fig. 6.4).

ii) Date and time are marked on a pencil line showing the bearing of thecall, starting from the observer’s position on the map. The distance fromobserver to calling animal is estimated and also marked to scale, and specialattention should be given to triangulating calls of the same group that weregiven at different times.

iii)Great care must be taken not to double-count groups, especially forspecies which travel rapidly over wide areas in a short time and call from differ-ent places (e.g. mangabeys). Information on species’ home-range sizes, home-range overlap, travel and foraging patterns (gathered during long-term studies)are important in determining how to reduce this type of error.

iv)Supplementary information can be added to the species’ maps,recording those animals seen, but not recorded calling, to give a fuller pictureof all the groups present.

Advantages/limitationsSince most primate groups call at some time during the day, and the call

can be heard over distances greater than are detectable by sight, inclusion ofcalling records greatly increases the sample size of encounters for a unit sur-vey effort. For example, on three morning surveys by two observers inKakamega forest (Kenya), there were 86 encounters with primates (sightingsand calls) of which 63% were calls of animals that were not seen (Davies, pers.obs.).

This method gives accurate information on the numbers of groups in agiven area for those species that are vocal during the survey period. Quietergroups, species, and times of the year will all give lower quality results.

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6/12

3/12

3/12

3/12

4/126/12

6/12

5/12

5/12

Survey trail with 100m markers

Map of sightings and calls ofCampbell’s monkey,Cercopithecus campbelli,during a four-day survey (3–6December). Numbers refer todates. Groups sighted aresquared, and group calls areshown by arrows indicatingthe direction from the survey-or and the arrow-head indi-cates the estimated locationof the group.

For species with home rangesof 20–50ha, surveys by smallteams for 20 days, over 6–12months, give good spreadindications of group densities.

Fig. 6.4: Mapping calls and sightings

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6.3.3 Sweep surveysIn practice, field workers make the most of all their field records by com-

bining information on sightings and calls. This can be done during transectwalks, but even more information can be gained when the surveys are carriedout along parallel transects on a survey grid by a number of surveyors workingsimultaneously. These are called sweep surveys (Whitesides et al., 1998).

Equipment/personnel� survey grid cut and mapped (see below)� at least three experienced field observers

Procedurei) A rectangular survey area has to be prepared, with three or more sur-

vey transects running parallel to each other, spaced at 100-m intervals, andextending for at least 1km. They should be linked at either end by perpendicu-lar trails, to get surveyors to the start points quickly and quietly. All paths aremarked at 50-m intervals.

ii) Soon after dawn, the surveyors should assemble at the start of theirsurvey trails and travel slowly and quietly along the path, beginning at a pre-arranged time (having synchronised watches beforehand). The surveyors moveforwards in a single front, stopping occasionally to make field records. To keepthe line of surveyors coordinated, several pre-determined restart points shouldbe marked along the survey routes.

Recordingi) When a primate is sighted, its position and the group-spread are

marked on a scale map (e.g. 10mm: 50m). All primate group sightings and callsare recorded (as noted in sections 6.3.2 and this section above).

ii) By noting the time of all records (sightings and calls), simultaneousrecords of the same group by different observers can be mapped, therebyavoiding double-counting of the same groups.

Data analysisi) At the end of the survey, all surveyors reassemble and a map is com-

piled for each species from all records collected. Once the map has been com-pleted for a number of repeat surveys, separate primate home ranges can bemarked, and the number of groups within the survey area and its vicinity canbe counted.

115

ii) Some groups’ home ranges will fall wholly within the survey grid, butothers will be partly outside. Whitesides et al. (1988) considered groups havinghome ranges in excess of 80% inside the survey grid as being within the areasurveyed, groups having 80–30% inside the survey grid as half a group, andgroups with 30% or less of their home ranges inside the grid were regarded asfalling outside the survey area. By adding whole groups and half groups, thenumber of groups/km2 can be calculated.

iii)Detailed information on the size of primate groups, and their age/sexcomposition, combined with information on the body weights of different typesof animals (eg adult males, juveniles, females, etc.), can then be used to calcu-late population densities and biomass.

Advantages/limitationsThis method provides very reliable and accurate estimates of absolute

group densities, plus solitary individuals, within a known survey area. It can beverified by repeated sweep surveys over time to take account of seasonalbiases.

If the sample area is representative of the forest as a whole, then theresults from these surveys can be extrapolated to wider areas. The disadvan-tages of this method include the time taken to build up an accurate picture ofgroup densities, the large number of surveys required, the need for a team ofthree or more experienced surveyors (although a team of just two can allow tri-angulation on calling groups), and clearing and maintenance of the transect grid.

Rapid sweepsUsing the same principle as the sweep surveys, but in circumstances

where there is only one surveyor, the system can be modified to a rectangularsurvey area (1km x 500m, depending on the species being surveyed), in whichall sightings and calls of primates are recorded onto accurate maps. Over time,a picture of the number of groups in the area builds up, although the possibilityof missing groups in the centre of the survey rectangle are higher than for thesweeps, and groups on the edge may also be missed.

In Sierra Leone, data on relative primate abundance was gathered by asingle observer using survey rectangles of 1km x 500m (e.g. Davies, 1987).Rapid sweeps have also been used in the small patches of forest along theTana River in Kenya (Butynski & Mwangi, 1994), where pairs of observerssearched in a zigzag fashion through parallel swathes of forest with each sur-vey team’s route separated by about 100–150m. The survey routes were care-fully mapped, and plenty of time taken to search for primates. At the end of thesurvey, all teams met and discussed results before group encounters weremapped and the numbers of groups in each patch calculated.

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6.4 ConclusionsThere are a range of primate survey methods that have been adapted

for particular conditions and resource constraints, many of which depend oncombining records of primate calls and sightings. Selection of any one methodshould be determined by the question that has to be answered, and care mustbe taken to allocate the necessary resources required (e.g. time, personnel,transport, cash, etc).

Given the problem of resource and personnel constraints, line transectsare a useful and common survey method. They are practical for determiningthe relative density of primates at different sites as long as there are sufficientencounters to determine transect width. Sweep surveys are most useful fordetermining primate group density in areas of about 1km2.

Whatever survey method is being used, a rule of thumb is to gather asmuch field information as possible, during transect walks, when in the camp,when meeting with local hunters and villagers, and so on. All of this will helpimprove the interpretation of field survey results.

6.5 References

Bearder, S., Honess, P.E. & Ambrose, L. (1995). Species diversity among galagos, with special ref-erence to mate recognition. In: Creatures of the Dark: The Nocturnal Prosimians, pp 331–352.(Eds. L. Alterman, G.A. Doyle & M.K. Izard). Plenum Press, New York, USA.

Blom, A., Almasi, A. & Heitkonig, I.M.A. (2001). A survey of the apes in the Dzanga-Ndoki NationalPark, Central African Republic: a comparison between the census and survey methods of estimat-ing the gorilla (Gorilla gorilla gorilla) and chimpanzee (Pan troglodytes) nest group density. Afr. J.Ecol. 39(1): 98–105.

Buckland, S.T., Anderson, D.R., Burnham, K.P. & Laake, J.L. (1993). Distance Sampling:Estimating Abundance of Biological Populations. Chapman & Hall, London, UK.

Butynski, T.M. (1984). Ecological survey of the Impenetrable (Bwindi) Forest, Uganda, and recom-mendations for its conservation and management. Unpublished report to the Government ofUganda. pp. 150.

Butynski, T.M. & Kalina, J. (1998). Gorilla tourism: a critical look. In: E.J. Milner-Gulland & R. Mace(eds), Conservation of Biological Resources, pp 280–300. Blackwell Science, Oxford, UK.

Butynski, T.M. & Mwangi, G. (1994). Conservation status and distribution of the Tana River redcolobus and crested mangabey. Unpublished report to the Kenya Wildlife Service. pp. 67.

Chapman, C.A., Balcomb, S.R., Gillespie, T.R., Skorupa, J.P. & Struhsaker, T.T. (2000). Long-termeffects of logging on African primate communities: a 28-year comparison from Kibale National Park,Uganda. Conserv. Biol. 14(1): 207–217.

Charles-Dominique, P. (1977). Ecology and Behaviour of Nocturnal Primates: Prosimians ofEquatorial West Africa. Duckworth, London, UK.

Cowlishaw, G. (1999). Predicting the pattern of decline of African primate diversity: an extinctiondebt from historical deforestation. Conserv. Biol. 13(5): 1183–1193.

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Davies, A.G. (1987). The Gola Forest Reserves, Sierra Leone: Wildlife Conservation and ForestManagement. IUCN, Gland, Switzerland.

Davies, A.G. & Oates, J.F. (1997). The Colobine Monkeys: their Ecology, Behaviour andConservation. Cambridge University Press, Cambridge, UK.

Gautier-Hion, A., Bourliere, F. & Gautier, J-P. (1988). A Primate Radiation: Evolutionary Biology ofAfrican Guenons. Cambridge University Press, Cambridge, UK.

Grubb, P.A., Jones, T.S., Davies, A.G., Edberg, E., Starin, E.D., Hill, J.E. (1998). Mammals ofGhana, Sierra Leone and The Gambia. Trendrine Press, UK.

Hall, J.S., White, L.T.J., Inogwabini, B.I., Ilambu, O., Morland, H.S., Williamson, E.A., Saltonstall, K.,Walsh, P., Sikubabuo, C., Dumbo, B., Kaleme, P.K., Vedder, A. & Freeman, K. (1998). A survey ofGrauer gorillas (Gorilla gorilla graueri) and chimpanzees (Pan troglodytes schweinfurthii) in the KahuziBiega National Park lowland sector and adjacent forest in eastern Congo. Int. J. Primatol. 19: 207–235.

Hashimoto, C. (1995). Population census of the chimpanzees in the Kalinzu Forest, Uganda: com-parison between methods with nest counts. Primates 36: 477–488.

McGrew, W.C., Marchant, L.F. & Nishida, T. (1998). Great Ape Societies. Cambridge UniversityPress, Cambridge, UK.

National Research Council. (1981). Techniques for the Study of Primate Population Ecology.National Academy Press, Washington D.C., USA.

Oates, J.F. (1996). African Primates: Status Survey and Conservation Action Plan. IUCN, Gland,Switzerland.

Oates, J.F., Abedi-Lartey, M., McGraw, W.S., Struhsaker, T.T. & Whitesides, G.H. (2000). The pos-sible extinction of a West African Red Colobus monkey. Conserv. Biol. 14(5): 1526–1532.

Peres, C. (1999). General guidelines for standardising line-transect surveys of tropical forest pri-mates. Neotrop. Primates 7(1): 11–16.

Plumptre, A.J. (2000). Monitoring mammal populations with line transect techniques in Africanforests. J. Appl. Ecol. 37: 356–368.

Plumptre, A.J. & Reynolds, V. (1997). Nesting behavior of chimpanzees: Implications for censuses.Int. J. Primatol. 18: 475–485.

Plumptre, A.J. & Johns, A.D. (2001). Primate populations. In: Wildlife-logging Interactions in TropicalForests. (Ed. by R.A. Fimbel, A.Grajal, & J. Robinson). Colombia University Press, New York, USA.

Skorupa, J.P. (1986). Responses of rainforest primates to selective logging in Kibale forest,Uganda: a summary report. In: Primates: the Road to Self-sustaining Populations, pp 57–70. (Ed.K. Benirschke). Springer-Verlag, New York, USA.

Skorupa, J.P. (1987). Do line-transect surveys systematically underestimate primate densities inlogged forests? Am. J. Primatol. 13: 1–9.

Tutin, C. & Fernandez, M. (1983). Recensement des gorilles et des chimpanzés du Gabon. CIRMF,Gabon.

Tutin, C.E.G., Parnell, R.J., White, L.J.T. & Fernandez, M. (1995). Nest-building by lowland gorillasin the Lope-Reserve, Gabon – environmental-influences and implications for censusing. Int. J.Primatol. 16: 53–76.

White, L. & Edwards, A. (2000). Conservation Research in the African Rain Forests: a TechnicalHandbook. Wildlife Conservation Society, New York, USA.

Whitesides, G.H., Oates, J.F., Green, S.M. & Kluberdanz, R.B. (1988). Estimating primate densitiesfrom transects in a West African rain forest: a comparison of techniques. J. Anim. Ecol. 57:345–367.

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Form 6.1: Primate Recording Sheet for Line TransectsSurveyor: Field sheet ref: Date:(total observers): (dd/mm/yy)

Address:

Survey site: Altitude: Aspect:

Latitude: Longitude: UTM (if available):

Vegetation: Human disturbance:

Season: Weather: Lunar phase: Temperature:

Transect length: Start time: End length:

Other:

Time

Species

Detection

Bearing

Transect-AnimalDistances (m)

Transect-EstimatedGroup Centre (m)

MAP (m from start)

Estimated & SightedNumber

Age/Sex

Group Spread

Activity

Reaction

Notes

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Form 6.2: Recording Sheet for N

est Counts

Surveyor:

Address:

Date:

Field sheet ref:

(total observers)(dd/m

m/yy)

Survey site:

Vegetation:

Weather:

Latitude:Longitude:

UT

M (if available):

Altitude:

Transect length:

Start tim

e:E

nd time:

Other:

Distance

Species

Nest

Dim

ensionsS

tate/ageD

istanceA

dditional observationsfrom

startfrom

transect (m)

(km)

Notes: D

istance from start =

from start of transect; species (based on evidence from

faeces, hair other evidence); nest – in tree or on ground; woody or herbaceous, etc; dim

en-sions (w

idest and narrowest diam

eter in cms); state\age: A

= fresh, still w

ith animal odour; B

= recent, still w

ith green leaves, but no odour; C =

old, intact but no green foliage;D

= very old and disintegrating (after W

hite and Edw

ards, 2000); distance from transect – perpendicular distance from

the transect (m)

120

Form 6.3: Primate recording sheet for mapping calls

Surveyor: Field sheet ref: Date:(total observers): (dd/mm/yy)

Address:

Survey site: Altitude: Aspect:

Latitude: Longitude: UTM (if available):

Vegetation: Human disturbance:

Season: Weather: Lunar phase: Temperature:

Transect length: Start time: End length:

Other:

Time

Species

Detection

Bearing

Observer–Animal (m)

MAP (m from start)

Age/Sex

Group Spread

Activity

Reaction

Notes

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7.1 BiologyBirds are the best-known group of vertebrates. There have been numer-

ous studies on forest birds of eastern Africa, and most species are readily iden-tifiable using field guides and standard reference works. Birds play an impor-tant role in forests as pollinators of flowers and dispersers of seeds. Many ofthe smaller species also eat large numbers of insects and other arthropods.Birds, in turn, are preyed upon by reptiles, mammals, and other birds. TheAfrican crowned eagle, Stephanoaetus coronatus, is an example of a toppredator in some forests, and may take prey as large as colobus monkeys.

Birds are often considered as a useful indicator group, either for monitor-ing environmental change (see Furness et al., 1993) or for assessing biodiver-sity importance (Thirgood & Heath, 1994; Stattersfield et al., 1998). Birds as agroup have many characteristics that make them good indicators: they arewell-studied, taxonomically stable, easily surveyed, widely-distributed acrossalmost all habitats, and include both generalised and specialised species.There are enough bird species (more than 1,300 in East Africa; more than2,170 in Africa and Madagascar) to make meaningful comparisons betweensites, but few enough that taxonomic and identification problems are rarely anissue. However, there are few precise details and guidelines on how birds canbe used as indicators. Bennun & Fanshawe (1998) discuss bird surveys to

7. BirdsLeon Bennun and Kim Howell

Jam

eson

’s w

attle

-eye

(P

laty

ster

ia ja

mes

oni)

122

evaluate the effects of forest management, while Howard et al. (1998) demon-strate that information on birds can be used to select a set of priority sites forbiodiversity conservation, even if the distributions of birds and other animalsand plants are poorly correlated.

Categories of forest-dependenceAbout one-third of the bird species in East Africa are found in forest.

However, the extent to which they depend on forest differs. Bennun et al.(1996) list forest birds in Kenya and Uganda, in three categories:

� FF species (forest specialists) are the true forest birds, characteristicof the interior of little-disturbed forest. They may persist in secondary forest andforest patches if their particular ecological requirements are met. Where theydo occur away from the interior, they are usually less common. They are rarelyseen in non-forest habitats. Breeding is almost invariably within forest.

� F species (forest generalists) may occur in undisturbed forest but arealso regularly found in forest strips, edges and gaps. They are likely to be morecommon there and in secondary forest than in the interior of closed-canopyforest. Breeding is typically within forest.

� f species are birds which are often recorded in forest, but are notdependent upon it. They are almost always more common in non-foresthabitats, where they are most likely to breed.

These categories can be applied to forests elsewhere in Africa, althoughthe same species may fall into different categories in different parts of its range(Bennun et al., 1996).

The forest-specialist birds tend to have smaller distribution ranges thanthe other categories, and are more likely to be threatened with extinction(Bennun et al., 1996). This is not surprising, because they are less tolerant ofhabitat disturbance than other species. The exact ecological requirements ofmost forest-specialist species are still poorly known, but many seem to use anarrow range of habitats within the forest undergrowth or the canopy. Changesin the forest structure, brought about, for example, by selective logging, maymake it difficult for them to survive and reproduce successfully. Removal of for-est causes them to disappear entirely. In most cases, conversion to plantationswill have a similar effect: very few forest birds survive in plantation forest,except where indigenous tree species are planted.

Some forest birds are long-distance migrants (for example, the Africanpitta, Pitta angolensis), while others (such as some parrots, hornbills and bar-bets) may make long movements in search of patchy supplies of food. Many,however, spend their whole lives within a small area of forest and may bereluctant to cross even small gaps between forest patches (Newmark, 1991).Forest species that migrate altitudinally between montane and lower-altitude

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forests present a particularly complex conservation problem, as forests at bothaltitudes must be maintained.

Feeding guildsIf comparisons are to be made across space (i.e. between sites) or time

(i.e. monitoring at a particular site) then it is often useful to be able to subdividethe data according to forest dependence and guild categories. Guilds aregroups of birds, not necessarily taxonomically related, that feed or behave in asimilar way – for example bark-gleaning insectivores or just insectivores areboth guilds. Bennun & Fanshawe (1998) show that these classifications can beuseful for understanding the effects of forest management, since differentguilds respond differently to particular structural changes. One advantage ofusing guilds or forest-dependence categories is that they average out the idio-syncratic responses of individual species, so that a more general patternemerges.

Plumptre & Owiunji (unpubl.) have developed the following set of feedingguilds for Budongo forest in Uganda (with codes for computerising data):

Feeding strategy Code

Frugivore FRFrugivore-insectivore FRINInsectivore

a. Sallying – from perch to flying insect INsab. Ground – feeds on insects in leaf litter INgrc. Gleaning c1: Gleans from leaves INglL

c2: Gleans from bark INglBGramnivore (seed-eater) GRGramnivore-insectivore GRINNectarivore-insectivore NECOmnivore (eats many types of food) OMRaptor

a: catches below canopy RAPbb: catches at canopy mainly RAPc

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Feeding heightDifferent bird species make use of different levels in the forest, so it is

important to record species that are being seen. Three simple categories canbe used:

1. feeds at or within three metres of ground level GRD2. feeds in the middle strata of the forest

or in understorey tree canopies MID3. feeds at forest canopy height (in tallest trees) CAN

This classification provides a useful level of detail (Bennun & Fanshawe,1998) and is recommended for application in other African forests.

If survey data are to be lumped into forest-dependence or guild cate-gories, this may affect the survey methods that are chosen. Not all surveymethods produce data that can be pooled in this way (see section 7.3 below).

7.2 Management issuesIntact natural forest is a diminishing habitat everywhere. This puts forest-

specialist bird species at risk. In places where large blocks of forest havebecome fragmented, bird populations that were once continuous are now splitinto isolated units that may have limited interchange with each other (e.g. Lenset al., 1999). Fragmentation has other negative effects: fragments have rela-tively more edge and less interior than large blocks; they are especially vulner-able to habitat degradation; and they may be easier for predators or parasitesto penetrate. Local extinctions have already been demonstrated in small forestfragments across East Africa (e.g. Tanzania: Newmark (1991); Kenya: Brookset al. (1998); and Uganda: Dranzoa (1993)). In the Taita Hills, the asymmetry ofbirds’ plumage features (fluctuating asymmetry, a sign of stress) increases insmaller forest fragments (Lens & van Dongen, 1999), and there may be con-comitant effects on population sex-ratios (Lens et al., 1998).

Management strategies to mitigate the effects of fragmentation mayinclude restoration or maintenance of habitat corridors (e.g. forest strips alongriver valleys) and more effective protection from human disturbance. Wherelarge forest blocks remain, zoning and control of forest exploitation should bedesigned to prevent habitat fragmentation occurring in the first place.

Habitat degradation also has negative effects on forest birds. The popu-lations of forest-specialist species decline as the structure of the habitat ismodified (see Bennun & Fanshawe, 1998 for a review). Mechanised logging isthe most conspicuous form of habitat degradation, but severe damage may

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also be done by non-mechanical methods such as pit sawing. On a smallscale, logging opens up gaps that mimic natural tree-falls and increase thediversity of species – but at the expense of the sensitive forest-interior birds.Exploitation for poles and fuelwood, and grazing by livestock, can causeserious problems for forest-specialist species. Collection of fallen deadwoodaffects insect populations, and thus birds too. Hole-nesting birds such as wood-peckers, barbets and hornbills rely heavily on standing deadwood or old, over-mature trees where nest-sites can be found or excavated (Newton, 1994; DuPlessis, 1995). A forest that is well managed for timber, with dead or dyingtrees carefully removed, may be very badly managed for birds (and other biodi-versity).

Tye (1993) reviews many of the relevant conservation issues with exam-ples from Tanzania. Generally, arguments for the sustainability of these formsof forest use must be critically assessed; in practice, sustainability usuallymeans a particular trade-off between economic benefits and biodiversity loss.Deciding whether such a trade-off is acceptable or not requires detailed ecolog-ical knowledge about the species of conservation concern and a monitoringprogramme to assess the effects of forest-use, both local (e.g. Hall & Rodgers,1986) and commercial.

Some bird species are hunted for food. In East Africa at least, this is notusually a concern for most forest species. However, it may be a problem for afew, such as forest francolins; for example, hunting already poses a threat tothe Udzungwa partridge, Xenoperdix udzungwensis, which has a restricted dis-tribution range in Tanzania. Capture of birds for the live-bird export trade affectsa small number of forest species, such as the grey parrot, Psittacus erithacus.Any legal offtake of birds, for local use or export, must be controlled properlyand based on detailed distribution and population studies for the speciesconcerned. Such control measures do not currently exist.

Birds can themselves be used as a management and conservation tool(Bennun, 1999; Bennun & Njoroge, 1999). At one level, they are likely to be theeasiest group to monitor if changes in forest biodiversity need to be assessed.At another level, they provide an excellent focus for conservation educationand action. For example, site-support groups with a birdwatching emphasis arealready active around several forest Important Bird Areas in Kenya.Birdwatching has great tourism potential in East African forests, and can pro-vide a source of local employment and revenue generation. Although birds stilllack the public profile of large mammals, in East Africa they are receivingincreasing attention and increasingly high priority in conservation and manage-ment. For example, in Tanzania, the finding of a new species of bird (as well asof other vertebrates) helped catalyse the establishment of that country’s firstforest National Park.

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7.3 Methods

GeneralSurveys of forest birds may be undertaken for a variety of reasons,

including:� characterising the avifauna of a little-explored site;� comparing the bird communities of different forests, in order to set

conservation priorities;� tracking changes in bird communities in relation to forest management

(a form of monitoring: see below);� investigating the distribution and status of particular birds of interest

within a forest, or among a set of fragments.The different kinds of surveys differ in whether they require simple lists,

measures of relative abundance, or measures of absolute abundance. Simplelists are the easiest kind of information to collect. However, with very little extraeffort it is possible to collect information on relative abundance. This allowscomparison of sites within and between forests and is generally much moreuseful. It is at this level that most survey work is carried out. Assessing theactual population densities of birds requires considerably more work, andshould only be undertaken if the extra information really justifies the effort.

This chapter provides only a brief outline of the survey methods mostuseful for forest birds, many of which have been field-tested in Kenya andUganda. For more information and discussion, see Pomeroy (1992) and Bibbyet al. (1998, 2000).

Inventory versus monitoringInventory (finding out what species are in a particular site) and monitor-

ing (tracking changes over time) are at opposite ends of a spectrum of surveytypes. It is important to be clear about what kind of work you are doing, asotherwise much valuable effort can be wasted.

Strictly, monitoring implies assessing changes against some target valueor threshold. With forest birds, we are more often involved with surveillance – aseries of surveys over time. In either case, it is important that data are collect-ed in a highly standardised way, on a regular (though not necessarily frequent)basis. You need to be able to repeat the same kind of data collection at thesame place at the same time. Some useful background and guidelines on sur-veillance and monitoring can be found in Goldsmith (1991), Stork & Samways(1995), Tomas Vives (1996) and Bennun (2000, 2001).

The key feature of monitoring (including surveillance) is consistency.Often, this means that you will only be able to survey a small portion of a

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particular site. Entire bird communities can be monitored, but monitoring oftenconcentrates on one or a few key species or species-groups that are particular-ly significant. For example, depending on your interest or the threats andchanges facing a particular site, monitoring surveys might focus on a threat-ened species, or a particular feeding guild like large frugivores. Because moni-toring aims to detect changes, it is important to minimise the sampling errors inestimates (see below). This means careful sample design and high-effort, low-coverage surveys. Suitable techniques for monitoring are those that can beexactly repeated in the same places time after time, and that give accurateestimates – for example, fixed- and variable-width transects and point counts.

With inventory, the concern is usually comparisons in space (with othersites) rather than comparisons over time. The aim is to build up as complete apicture as possible of a site’s avifauna. Because bird distributions are oftenpatchy, it is important to cover as much area as possible. Since inventory oftenhas to be rapid, this means that surveys at a particular location may be rela-tively superficial. To make sure the species list is complete, different techniques(such as mist netting, playback and timed species-counts) may need to beused together, and all available habitats investigated. Absolute abundancemeasures are usually unnecessary for inventory work – relative abundance isenough, so long as similar approaches have been used at the comparisonsites.

Good inventory techniques will thus cover large areas and produce longspecies-lists quickly. Examples below include timed species-counts andMacKinnon lists (and their variants).

IdentificationTo survey birds you need to be able to identify them, both by sight and

sound. This is not easy in forests. Building identification skills takes time andeffort, although going to the field with more experienced birders who are willingto teach and encourage you is probably the best way to improve identificationskills rapidly. You can also build your knowledge of species by examining spec-imens in the collection of a museum and/or university, and through carefulstudy of reference books and other literature. The number of useful referencesis increasing, including:

� illustrated field guides or checklists. For East Africa, the books ofchoice are Stevenson & Fanshawe (2001), for the whole region(except Ethiopia), and Zimmerman et al. (1996), an essential hand-book for Kenya and northern Tanzania that includes many birds ofUgandan forests. Many good guides are available for southern Africa,such as Sinclair et al. (1997) and Newman (2000). Van Perlo (1999)covers Zambia, Angola and Mozambique, omitted by most other

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guides. In West Africa the choice is more limited: Serle & Morel (1992)covers the whole region but it is out of date (and out of print inEnglish). There are a few field guides for particular countries, such asSeneGambia (Barlow et al., 1997) and Sao Tomé and Príncipe(Christy & Clarke, 1998).

� Birds of Africa, a multi-author, multi-volume handbook published byAcademic Press, and now into its sixth volume (Fry et al., 2000), withone more volume due. Certainly not one for the field, since each vol-ume weighs several kilograms, but an essential reference work.

� The African Handbook of Birds by Mackworth-Praed & Grant (1955–1973; six volumes) provides detailed information and is very useful foridentifying birds in the hand, especially where no modern field guide exists. The nomenclature is somewhat out of date, and the illustrationsare scanty and inadequate, but these volumes remain invaluable.

� Notes on particular difficult groups, in periodicals such as the AfricanBird Club Bulletin and Africa: Birds and Birding, or regional publica-tions like Scopus and Kenya Birds (e.g. Allport et al. (1996) onilladopses, Turner & Zimmerman (1979) and Bennun (1994) onKenyan greenbuls).

There are now good commercial compilations of sound recordings foreach major region of Africa: West (by Claude Chappuis); East (by Brian Finch,published alongside Stevenson & Fanshawe, 2001), and South (by GuyGibbon and others). These are very valuable reference sources for forest birdsurvey work, and will amply repay study. Bear in mind that there is substantialindividual variation in calls, and that bird species do not always sound thesame across their entire range. Many researchers and birdwatchers also keeptheir own sets of recordings and may be willing to loan them; other useful com-pilations are listed in Pomeroy (1992).

Learning the birds that you are likely to encounter in a specific area, bysight and sound, will save much time and effort in the field. If you can reliablydetect differences between birds, so that the number of different species yousee can be recorded fairly accurately, this will enable you to collect meaningfuldata even if you cannot be sure of all identifications. Indeed, if you find yourselfunable to identify a particular species in the field, even after having consulted afield guide or birding companion, then it is important to note down importantfeatures of the bird (e.g. general size/colour, beak colour/shape, eye colour,etc.) or to make a rough sketch. Do not spend too much time doing this,because the distraction may cause you to miss other sightings. With practice,your ability to record features of birds in your notes will improve, allowing youto identify more birds using the reference works.

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Especially when you are starting off, it may be wise to note which birdsyou identify on the basis of their calls alone. This will enable you to go back toyour data and correct your records (in the event of allocating the wrong nameto a particular bird call).

Ideally, you should identify all the birds you record reliably to the level ofspecies. If you are unable to do so, then try and identify them reliably to thelevel of the group or genus (e.g. greenbul or flycatcher). Although birds aremuch easier to identify than many other groups of animals, they are still chal-lenging – especially when you are using calls. Always be cautious, and takeyour level of experience into account. Never be tempted to name a bird unlessyou are really certain of the identification and can justify it from your notes ifnecessary. Write down doubtful cases as ‘Unidentified greenbul’ (or whatever),or in the worst case, ‘Unidentified bird’. Failing to make an identification ismuch preferable to making the wrong one.

A note on samplingA detailed discussion of sample design is beyond the scope of this chap-

ter, and more information on sampling for bird surveys can be found inPomeroy (1992) and Bibby et al. (1998). However, some general points arediscussed by Bennun & Fanshawe (1998):

i) Forest bird survey data tend to be noisy. If forests or forest blocks areto be compared statistically, there must be an adequate number of samplingunits.

ii) This means trying to balance the number of replicates, the time andeffort needed to carry them out, and the size of the sample that can be collect-ed in each case. For instance, if time allows you to run a total of 10km of tran-sects in each block of forest, how should you divide these up? One 10km tran-sect is probably not a good idea, but a hundred 100m transects might not beuseful either – the number of birds you would record along each one might bevery low. Most probably, something in between would be more suitable, withtransect length determined by the number of birds you expect to record and thenumber of these transects determined by how much time you have.

iii) Survey results can be strongly influenced by season, time of day andlocal habitat variation (including elevation). It is essential to minimise bias inyour data by taking these sources of variation into account (e.g. by conductingcounts at different sites during the same seasons, randomising count orderacross the day, and stratifying your sample to take habitat and altitudinalvariation into account).

If you intend to do transect work, or carry out mist netting, you will needto think about the location of your lines. Usually these should be randomised,as far as possible, within each stratum of your sample (but if you are mainly

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interested in building up a species list then you will want to place mist nets in avariety of micro-habitats – also see section 5.3.3). It is often desirable to useexisting small trails and paths, rather than destroying more vegetation by cut-ting your own. Be aware, however, that trails are themselves often aligned in ahighly non-random way.

Transect lines do not necessarily have to be entirely straight. Somereconnaissance to map out trails may be necessary (and is almost always use-ful) before survey work begins. When trails are mapped they can be partitionedinto convenient sections of equal length. By giving each section a number, youcan select sections for sampling using random number tables.

Alternatively, especially if you do have to cut your own trails, you can layout transects or mist net lines systematically. For example, you might decide tosample at every 500m alternately to left and right along a line bisecting the for-est. Systematic sampling has the advantage of simplicity and of covering thewhole study site (by definition, random sampling does not always do this).However, where there is a regular pattern in habitat variation, such as evenlyspaced ridges and valleys for instance, it can potentially lead to biased results.See also section 7.3.11 for tips on suiting the method to the bird.

7.3.1 General surveysA general survey consists of recording the species, and sometimes num-

ber, of birds seen and heard in an area. After a period of observation, a broadindication of abundance, such as ‘regular’, ‘common’ ‘rare’, and so on, can begiven to each species.

Site selection, procedure and recordingA regular record is kept of bird species seen and heard during walks (or

at any other time, e.g. around a base camp or while watching a fruiting or flow-ering tree). Usually, observers try to cover as much of an area as possible andinvestigate all major habitats and micro-habitats, in order to maximise the num-ber of species recorded. Observers might also use play-back and mist nettingto try and detect inconspicuous undergrowth species. Preferably, habitat andnumbers (at least for flocking species) should be noted for each record.

Advantages/limitationsThis is the least useful approach with respect to quantitative results and

comparative work, but it does allow an initial species list to be drawn up. It isdifficult to standardise observer effort, and impossible to make any but thebroadest comparisons with other sites.

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If a survey is being planned specifically for birds, then it is much better touse a more systematic approach (such as timed species-counts). If the birdwork is being done as a side-line, perhaps while conducting botanical surveys,then a general survey may be all that is possible. In any survey it is importantto record ad hoc observations of birds (i.e. casual records in addition to thoseon scheduled counts) as these may add substantially to the species list.

7.3.2 Timed species-counts (TSCs)The timed species-count technique provides a quick and simple method

for gaining a measure of relative abundance of canopy and mid-level birdspecies in a fairly large, defined area. It has the advantage of covering a biggerarea than point counts or transects (see below), and it is not tied down to par-ticular localities or lines. Thus it is possible to build up an overall species listmuch faster.

TSCs are essentially repeated species lists, on which are indicated thefirst time when each species is first positively identified by sight or sound(Pomeroy & Tengecho, 1986; Pomeroy & Dranzoa, 1997). Species receive acumulative score according to when they were first recorded on each count:species that are observed more frequently receive higher mean scores, as theytend to occur early within a count as well as in a high proportion of counts.TSCs were developed initially for use in open habitats, but have been modifiedin Kenya for application in forests.

Site selectionAs far as possible, TSCs should be well spread over the whole study

area being surveyed. They should also take in all the different micro-habitats(such as different forest types on ridges and along streams). During the count,there is no need to keep to a set path, and you can wander off to investigatesounds of bird activity, fruiting trees, and so on. If you are surveying forestbirds, it is usually a good idea to avoid going into areas of entirely differenthabitat, such as grassland or cultivation, as this could obviously give you mis-leading results. If you have a GPS, it is useful to record the start and endpoints of each TSC.

If you work in more than one study site within a forest, you should carryout the same number of TSCs in each.

Procedure and recordingi) The observer walks slowly and quietly along a path in the forest for a

fixed time period: 40 minutes has been used in Kenya, 60 minutes in Uganda.

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ii) In its simplest version, when the observer positively identifies a partic-ular species for the first time during that count, the species is recorded alongwith the time. In the modified version for forests, a note is also made, using asimple code, as to whether the birds are above or below 3m from the ground,and whether they are more or less than 25m from the observer’s present posi-tion or intended route. In this modified version, it is important to note the firsttime the bird is recorded within these limits: i.e. above 3m from the ground andwithin 25m from the trail. Only this information is used in calculating the TSCindex. Data may be entered on Form 7.1.

iii) The 3m limit excludes hard-to-detect understorey birds, which thistechnique samples inefficiently. The 25m limit removes some of the bias due tonoisy or conspicuous species, which tend to be identified early in a count andthus receive high scores (Bennun & Waiyaki, 1993). Records outside these lim-its are still valuable in compiling the overall species list. They can also be used,if so desired, to calculate an overall occurrence index, i.e. the proportion ofcounts on which the species is detected. The 3m limit was developed for usewhere undergrowth birds are being sampled by mist netting (see below) andmay be ignored when mist netting is not being used.

iv) In Kenya, the typical procedure has been to carry out at least 20TSCs for each study area (a particular sector of a forest). Several TSCs maybe carried out in a morning, separated by intervals of at least 10 minutes (intime) and 100m (in space). Timed species-counts are undertaken by a singleobserver, usually after the early peak of morning bird activity has decreased;this makes the results more consistent, and also allows workers to deal withthe early activity expected at the mist nets (see below). For standardisationpurposes, the suggested count period is between 08:30 and 12:00, but thismay need to be adjusted for different sites. General records of weather condi-tions (including wind) should be made at the beginning of each count.

v) This exercise should also be repeated as many times as possible,along different routes. Several people can conduct TSCs along different routesat the same time.

vi) If using the modified method, you will need to use a simple system ofsymbols, or a column on a form, to indicate whether or not the bird is above orbelow 3m and within or outside the 25m limit. It may also be a good idea, assuggested above, to indicate whether the bird was seen (‘s’) or only heard (‘h’).

Data analysisIn the modified method, the TSC index is based on only the records

above 3m and within 25m. To calculate this index, we need to know only thefirst time that each species is recorded within these limits; once a species has

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been recorded above 3m and within 25m, there is no need to record it when itappears again during the same count. For birds recorded outside the limits,each species need only be recorded once and the time is unimportant. Foreach count, each species is then assigned an index ranging from 0 to 4,depending on whether it was recorded during the first 10 minutes (= 4), secondten minutes (= 3), down to 0 for a species not recorded during that count. Anaverage score is then taken over all the counts. For an hour-long TSC, thescores go from 0 to 6 in the same way. The scores for the two systems can bemade comparable by adding 2.0 to the scores for the 40-minute counts.

Advantages/limitationsThe TSC is a good method for assessing relative abundance. It is not

necessary to record the number of birds detected, just the species, and youcan concentrate on detecting new species. This is an advantage for relativelyinexperienced observers who may need to spend more time on identification,and also for more experienced observers visiting a new site for the first timeand still familiarising themselves with the local birdlife. It is also useful whentrying to cope with mixed-feeding parties, when many species may passthrough in a very short time. The TSC index is a useful comparative measureof different sites and forests. It is not as good a method as the point count fordetecting shy birds of the forest interior, but appears to be just as efficient (per-haps more so) for sampling canopy species.

Pomeroy & Dranzoa (1997) show that species richness can be assessedfrom TSCs either from species accumulation curves or regression estimates.Measures of relative abundance for individual species from TSCs also correlatewell with those from transect counts (Pomeroy & Dranzoa, 1997) or timed tran-sects (see below: Bennun & Waiyaki, 1993). TSCs produce data on morespecies and in less time than traditional transects, thus making them more effi-cient. Because the TSC does not have to follow a set path over a set distance,it is much easier to carry out in forests than is a standard line transect. If theaim is to assess species richness (or the richness of a sub-group of species,such as forest specialists), or the relative abundance of particular species indifferent forests or compartments, then TSCs are a good method to use.

In the unmodified version of TSCs, scores strongly reflect detectability aswell as abundance. They thus cannot be used to compare even the relativeabundance of species that differ widely in their detectability (Pomeroy &Dranzoa, 1997). This problem is partially overcome by the modified versionwith a 25m distance cut-off (Bennun & Waiyaki, 1993). The relative abundance(compared to other species) of flocking birds is underestimated by TSCs(Bennun & Waiyaki, 1993), and TSCs do not adequately sample shy under-storey birds.

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However, the main problem with TSCs is that the indices are not veryeasy to handle mathematically. Each TSC index is a measure of relativeabundance for a particular species on a scale of 0–4 or 0–6. It is not clearwhether TSC scores can legitimately be summed to create a cumulative indexfor forest-dependence categories or for guilds. If summed abundance mea-sures for these sub-groups are needed, then it may be better to use anothermethod – perhaps a timed transect (see below). For this reason, in particular,TSCs may not be very useful for monitoring purposes (see Bennun &Fanshawe, 1998).

7.3.3 MacKinnon listsand related methods

MacKinnon lists (MacKinnon & Phillips, 1993; Bibby et al., 1998) alsoallow calculation of an index of relative abundance. In essence, you build up apicture of the richness of the avifauna and species’ relative abundance by com-piling a series of species lists – each with the same number of species. Thefaster the total number of species rises as you add lists, the greater the overallrichness. The more lists a particular species occurs on, the more abundant it is.

Fjeldså (1999) developed this method further for use in rapid assess-ment of forest avifaunas, using a 20-species list.

Site selectionAs for timed species-counts. Ideally, your effort should be well spread

across your study site and cover all micro-habitats. Simple MacKinnon listingrequires searching for birds in whatever may be the most efficient manner.Different ground should be covered from one list to another. The minimumnumber of lists needed for each study site is around 15.

The Fjeldså technique involves listing within a defined study site – in hiscase, of area 1.5 km2 in a particular forest type. Within this, you walk randomly,searching for and recording birds.

Procedure and RecordingIn the simple version, you search for and record each new bird species

until you have a pre-set number of species on your list – usually between 8and 20 (the more species-rich your forest, the higher the number on the listshould be). When the species total reaches the pre-set number, start anotherlist, on which the same species can appear again if you see or hear them.

Fjeldså’s method is similar, but you record every bird seen and heardthroughout the count. Fjeldså walked randomly within the study site from dawnto dusk, recording throughout. However, the method can just as well be applied

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for shorter periods – the minimum on one day being the time taken to acquire alist of 20 species.

Data analysisPlotting the total number of species recorded against the number of lists

included gives a curve that rises rapidly at first and then levels out, finallyreaching a plateau. This plateau level gives the observed species richness,which can be compared across sites (using the same number of lists, with thesame number of species in each list, for each site). This value is not the sameas the real, total species richness, but can be used to estimate it: Fjeldså(1999) gives a formula for this, based on Colwell & Coddington (1994).

Relative abundance of species can be expressed as the fraction of listson which a species occurs (Bibby et al., 1998). However, since each speciescan only occur once on each list, this will severely underestimate the abun-dance of common species. Fjeldså (1999) dealt with this problem by recordingevery bird seen or heard, whether a new species for the list or not. The totalnumber of records for each species can then be expressed as a percentage ofthe overall total. This is a similar approach to the timed transect method (seebelow). Relative abundances calculated this way correlated very strongly withmeasures derived from intensive point count observation in the same forests(Fjeldså, 1999).

Advantages/ limitationsThe simple MacKinnon list method does not produce reliable relative

abundances, which is a disadvantage for most studies. Fjeldså (1999) lists thefollowing advantages of the adapted method:

� time is used efficiently – all the time available is devoted to datacollection, rather than, for example, moving between transect lines or point count points;

� more information is gathered than in a total list of species seen: datacan be standardised and total species richness extrapolated;

� it produces reliable information on relative abundances (provided thatall the birds seen or heard are recorded);

� it is less influenced by the relative skills of observers, compared with timed species-counts. This is because you can take as much time as you need to identify a particular bird, and it does not matter whether you complete your list of 20 species in an hour or in a whole morning.

To obtain relative abundances with this method requires more effort thanwith timed species-counts, since all birds seen or heard have to be recorded,rather than just each new species. The reduced influence of relative skills isonly real if all observers can eventually identify all the birds they see or

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hear – no survey method will work well with very inexperienced observers. Withan experienced survey team, this approach differs very little from timedtransects (see below).

7.3.4 Timed transects (TTs)Timed transects (TTs) were developed for use in Kenyan forests as a

simple method of assessing relative abundance that did not suffer from someof the problems of the TSC. Timed transects measure the number of birds seenin a set time, rather than along a set distance.

Site selection, procedure and recordingThe timed transect technique is similar to the TSC, except that the

observer also records the numbers of birds seen or heard within the limitsdescribed for the modified TSC (i.e. above 3m and within 25m), each time abird is identified (not just the time a species is first detected). Species detectedoutside the limits are recorded separately in order to build up the species total.

Advantages/limitationsTimed transect and TSC scores are strongly correlated (Bennun &

Waiyaki, 1993), and the two methods share the same advantages of being sim-ple and quick to perform. However, because the actual number of birds isrecorded, the timed transect method is less susceptible to the biases of theTSC index in favour of conspicuous species and against flocking species.Because the TT index is the actual number of birds detected for each species,it is straightforward to produce cumulative scores for forest-dependence andguild categories.

However, TTs require more effort than TSCs. All birds within the limitsmust be identified and counted. It can be especially difficult to estimate thenumbers of birds that are only heard – some experience of the forest and thespecies may be necessary before this can be done with accuracy.

Timed transects could, in principle, be used for monitoring. However, it isdifficult to repeat exactly the same series of counts in the same places, and totie these down to other aspects being monitored (such as vegetation). Pointcounts or fixed-length transects are recommended for monitoring instead.

7.3.5 Fixed-width transect countsTransect counts have been used extensively in open habitats, but, in

closed forest, visibility is poor and the viable transect width tends to be narrow.It can also be difficult to lay down fixed-length transects in forest habitat. In the-

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ory, line transects provide a measure of absolute abundance; in practice, this isprobably not the case, as many birds are probably missed – although theresults of fixed-width transects are expressed as a density.

See the discussion of line transects in the mammals chapters (sections5.3.3 and 6.3.2).

Site selectionBecause transects start and stop at specific points, it is usually possible,

and desirable, to randomise their locations, or to use systematic sampling (e.g.at fixed distances along a grid). See the section on sampling above.

Procedure and recordingi) You can either use existing trails or grids, or cut your own. Along the

route you have selected, measure out and mark a trail of known length (a use-ful length might be 1km).

ii) The procedure is to walk the measured route quietly and slowly. Thebest time to do this is in the early morning or late afternoon (when birds aremost active), but, in any case, counts should be made at consistent timesacross different sites.

iii) Record all the birds you see within a fixed distance of each side ofthe selected route: distances between 10m and 25m are feasible depending onthe nature of the habitat (use Form 7.2). If birds are in groups note the numberseen. Record the time and species of each sighting (making notes/sketches ofany birds that you cannot immediately identify). Continue walking the transectand make sure that you look at all levels, from the ground to the tops of thetrees above the route.

iv) After completing the transect, go back over your notes and attempt toidentify any species you were unable to identify in the field using field guidesand other literature.

Data analysisTransect data can be used to give a measure of species richness, to cal-

culate diversity indices (see Magurran, 1988 and Pomeroy, 1992 for more infor-mation), and to give a density of individual species or categories/guilds within adefined area of forest. This area is the length of all transects walked multipliedby the width covered.

Advantages/limitationsFixed-width transects provide a measure of density (although this will

usually be an underestimate, as many birds may be missed). They also allow

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various diversity indices to be calculated, as there is an abundance associatedwith each species. However, this is rarely very useful in practical terms, and thebest measure of diversity is usually simply species richness.

Fixed-width transects are time-consuming and cover a relatively smallarea. They are, therefore, not a very efficient way of building up species lists.They take no account of differences in detectability of species between differ-ent habitat types (e.g. disturbed and undisturbed forest), and so can potentiallygive misleading density estimates. If reliable density measures of particularspecies are required, variable-width transects using distance sampling may bemore useful (see below).

Fixed-width transects can also be difficult to lay down, requiring at leastmapping and measuring, if not extensive cutting of trails. This takes a gooddeal of effort and may lead to unnecessary forest disturbance.

7.3.6 Fixed-width point countsAlthough excellent for surveys, TSCs and TTs are not really suitable for

monitoring purposes, and point counts have been used for this purpose(among others) in Kenya. A major problem with this technique, however, is thatvery few birds tend to be recorded, since point counts sample a relatively smallarea.

Site selectionIt is usually easiest to lay out point counts on a grid in a systematic way.

Random locations are also possible, but may be difficult and time-consuming tofind (and re-find) on the ground. You should attempt to make at least 50 pointcounts in each study site. In Kenya, a simple method of spacing out countswas devised. Counts were made along a cut transect every fifteen minutes, i.e.the observer spent eight minutes walking (fast) along the transect, followed byseven minutes waiting and counting at the point (see below).

Procedure and recordingi) The observer stands at a pre-determined point that forms the centre of

a count cylinder that extends from forest floor to tree tops. After a two-minutesettling-in period, the next five minutes are spent recording all the birds seenand heard within a radius of 25m (Form 7.2 may be used). These times can bevaried if necessary. Theoretically, a point count is supposed to detect all thebirds around a point at the moment the count starts. Therefore, there must be abalance between the time taken to search the area thoroughly, and the likeli-hood of birds not recorded in the count area moving into it during the count.

ii) The species and numbers of individuals are recorded for all birds with-in the limits. Species detected outside the limits can be recorded separately tobuild up the species list. It can be useful to record whether birds are above orbelow 3m height (regardless of whether mist netting is also being used) so thatundergrowth and higher-level birds can be distinguished. Bird communitychanges in response to habitat change can be different at these levels (Bennun& Fanshawe, 1998).

iii) Point counts should be made over a standard period; for monitoring inKenya this has been defined as 09:00 to 11:15, after the main mist nettingactivity of the morning (this would mean a maximum of eight counts perobserver per day, following the routine above). Usually, point counts are carriedout by a single observer, but it is possible to have an experienced observeraccompanied by a trainee.

Data analysisAbsolute densities for birds detected within the limits can be calculated

as the total number of birds recorded, divided by the total area covered by thecounts. It is also possible to calculate an occurrence index (the proportion ofcounts where a species was recorded, for all birds inside or outside the limits).

Advantages/limitationsPoint counts are useful for monitoring because they can be replicated

precisely: counts can be made in more-or-less exactly the same places, in thesame defined area of forest, on a future occasion.

Point counts also have the great advantage that habitat parameters canbe measured around each point, and related to the presence or density of thebirds. For example, Oyugi (1998) used point counts to assess bird abundancein Kakamega Forest, Kenya. After measuring habitat parameters at each point,he was able to develop predictive models for the density of various birdspecies, and for particular guilds and forest-dependence categories. Similarly,Fanshawe (1995) used point counts to compare birds in more- and less-dis-turbed habitats in Arabuko-Sokoke Forest, Kenya.

Point counts sample a relatively small area and the number of individu-als recorded for most species on most counts will be zero. This makes it diffi-cult to compare density estimates for particular species statistically. Oneapproach is to compare the proportions of counts where particular birds wererecorded. This loses important information, however. Another possibility is tocombine density estimates for guilds or forest-dependence categories, or tosub-sample blocks so that a set of point counts are combined into a single datapoint. The small area covered by point counts makes them unsuitable for mostrapid survey work, at least where the main objective is to draw up species listsand obtain a general idea of the avifaunal composition.

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7.3.7 Distance samplingDistance sampling provides a powerful set of methods for estimating

absolute abundance of particular species of interest (see Buckland et al.,1993). Distance methods take into account the fact that many birds that shouldbe detected during a transect or point count will actually be missed. They alsotake into account the fact that birds may not be equally easy to detect indifferent forest types.

Owiunji (1996, 2000) used point counts with distance sampling to mea-sure abundance of birds in different forest types in Budongo Forest. Kosgey(1998) used transects with distance sampling to assess the densities ofTurner’s eremomela, Eremomela turneri, in South Nandi Forest. Similar meth-ods were used by Musila (2001) to census Sokoke pipits, Anthus sokokensis,and Mulwa (2001) to study Taita white-eye, Zosterops poliogaster. In theUluguru Mountains, Tanzania, Tom Romdal (unpubl.) played back calls of theUluguru Bush-shrike, Malaconotus alienus, at fixed points, and estimated thedistance of responses.

Site selection, procedure and recordingDistance methods may be used in conjunction with either transects or

point counts. The basic procedure is as described above for fixed-widthmethods. However, in this case, there is no cut-off point at a particular dis-tance. Rather, all records (with group sizes) of the species of interest arenoted, together with their perpendicular distance from the transect line, or thepoint count observer.

Data analysisData are analysed using the programme DISTANCE (the software and

manual are available, free of charge, on the internet atwww.ruwpa.st-and.ac.uk/distance). DISTANCE uses the set of observed dis-tances to model detectability functions (the way in which numbers of recordsdecline with distance from the observer) and to give estimates of actual densi-ties. Different functions can be obtained for each species and for different habi-tat types (see also section 5.3.3).

Advantages/limitationsDistance sampling is a very effective and powerful method for a specific

purpose: obtaining reliable estimates of the actual abundance of focal species(e.g. a particular threatened bird whose population size is unknown). It isunlikely to be a method of choice for most biodiversity surveys. Obtaining dis-tances for each observation is time-consuming and difficult. For species that

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are rarely encountered, there may not be enough data to model thedetectability functions. Densities can only be obtained for the more frequentlyrecorded species, and estimating densities for forest-dependence categoriesand for guilds will not usually be possible.

Using playback of calls combined with distance sampling can be veryeffective for birds (like the aforementioned Uluguru Bush-shrike) that are skulk-ing, scarce, or hard to detect. This does assume, though, that the birds call inresponse as soon as they hear the recording. If the birds come closer to youbefore responding, the technique may provide biased estimates of abundance.

7.3.8 Mist netting and ringingAll of the above techniques will tend to miss or under-represent forest

understorey birds, which often tend to be difficult to detect and identify visually.Knowledge of vocalisations can help considerably, but some species are large-ly silent and others sing only at certain times of the year (see section 4.3.5).

The only means of overcoming this difficulty is to use mist nets. Mist net-ting and ringing are powerful techniques for surveying and studying birds, andhave been used to follow weight changes, moult, breeding seasons and move-ment in individual birds. Employing capture-mark-recapture techniques, it canalso be used to estimate population size.

However, mist netting and ringing require considerable expertise andextreme attention to detail, which can be acquired only through lengthy train-ing. If you will be using mist nets to capture, identify and possibly ring birds,special permission is required. You should contact the appropriate ringingscheme (e.g. the Ringing Organiser, East Africa Natural History Society, P.O.Box 44486, Nairobi) for advice. Mist netting and ringing should be carried outonly by competent and experienced persons and qualified ringers, who canhandle the nets and the birds ethically and safely. If birds are not handled prop-erly, you may affect both the results of your study and, more importantly, thelong-term survival of the population. If you are not a qualified ringer, it is yourresponsibility to ensure that at least one and preferably two qualified ringersare members of your survey team, and that they train others in the proper tech-niques of netting, handling, and ringing birds.

The nets are called mist nets because they are made of extremely finenylon thread and therefore are almost impossible to see when stretched out.They come in a variety of heights, lengths and mesh sizes, but all feature vari-ous numbers of shelves – a pocket of mesh suspended from a strong thread,which runs along the net. If the nets are set correctly, birds flying across the netline do not detect them. When they fly into the net, they drop into one of themesh pockets, and become entangled (Fig. 7.1). They can then be carefullyremoved, identified, banded and measured.

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Fig. 7.1: Examples of mist nets

Equipment� mist nets� poles (straight bamboo poles about 40mm in diameter are ideal – light

but strong)� string� bird bags (cloth bags with a draw-string, in which to hold netted birds)� rings (variety of sizes)1

� ringing pliers� ringing book (printed books2, or use a hardbound accounting ledger

and label the columns: these data must later be transcribed into the schedules for the ringing scheme under which you operate; see also the Ringing Form at the end of this chapter). A waterproof bag is always advisable.

� stop-end ruler� spring balances (sizes 50g max. and 100g max.)� tarpaulin or fly sheet to protect birds and ringers from the elements at

the ringing station� flagging tape (for marking net sites for location before dawn, etc.)

1 Available from: Ringing Organiser, Nature Kenya, PO Box 44486, Nairobi, Kenya

([email protected]); Ghana Wildlife Society ([email protected]);

Cameroon Ornithology Club ([email protected]).

2 Contact: Ornithology Department, National Museums of Kenya, P.O. Box 40658,

Nairobi; Kenya.

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Site selectionMist nets work best when they are set against a background of vegeta-

tion. That makes them less visible to birds. Forests usually provide a goodhabitat for netting, but open glades and canopy gaps should be avoided. Areaswith a very open understorey usually produce low capture rates too, while netsclose to streams or other water sources are often especially productive. If youare trying to obtain a representative sample, however, you will need to lay outyour nets along randomly or systematically located lines, stratified according tomajor habitat divisions, as explained above.

Procedure i) To set mist nets, you could use existing (reasonably straight) trails, or

cut runs about 1m wide, if the vegetation will not permit the net to be set as itis. The aim is not to clear a wide path, or to alter the vegetation, but simply tolet the net be set so that it is not in contact with branches or other vegetation.The ground over which the net will be placed should also be cleared of anyvegetation or obstacles (such as rocks) that will entangle the net. For a well-illustrated explanation on how to set mist nets, see Howes & Bakewell (1989).

ii) A commonly used size of mist net is 12m in length and 3m high, withfour shelves and a mesh size of about 30mm (1.25in). Longer and shorterlengths, and various mesh sizes, are also available. It is important to have thebottom shelf of the net resting close to ground level. Many forest birds aretaken only in the bottom shelf, or the one above it. However, beware of antswarms and small mammal predators, which might attack birds trapped closeto the ground – frequent patrolling is important.

iii) The nets must be checked frequently at not less than half-hour inter-vals (preferably more often), and the birds removed (by trained extractors only)and placed in cloth bags. The birds are then taken to a ringing station a littleway from the nets (close enough to be convenient, but far enough not to inter-fere with netting) where they are processed (identified, measured, weighed,ringed, examined for moult, brood patch, etc.) before release.

iv) Metal rings (termed ‘bird bands’ in North American literature), come inseveral different sizes, and the correct size must be fitted to the tarsus of anindividual. Each ring has its own number and instructions on it (e.g. in EastAfrica, the message ‘Send Museum Nairobi’). Ringing is not an essential partof bird surveys using mist nets. However, it is important that captured birds aremarked in some way, so that you can tell if you retrap them. This is usually themost convenient (and by far the most informative) way of doing so.

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Suggested surveying procedurei) This procedure has been used successfully for survey by mist nets

(with simultaneous timed species-counts) in Kenya.ii) The exact number of net sites used and the length of net set up will

vary according to the time available, i.e. the survey schedule, and the particularforest. The aim is to catch at least 40 birds per net site in order to have a rep-resentative sample. Since capture rates vary between forests, so will the net-ting effort required. For each defined study block, try to net over two sites, eachwith between 120–200m of net. Each site is netted for two consecutive morn-ings. The nets are operated for four hours after dawn each day. This standardi-sation allows comparison of capture rates per net metre hour. The importanceof using the same time relative to dawn is that bird activity patterns vary greatlybetween dawn, mid-day and evening. Experience has shown that capture rateusually drops off dramatically in the late morning, and that evening capturerates are usually lower than those of the early morning too.

iii) Nets are set in a straight line with no breaks, along transects cutthrough the forest. When possible, it is useful to net along the same transectsas those cut for other studies, such as botanical work. This saves much timeand effort, but it will still probably be necessary to clear the transect further(especially at ground level) to make it suitable for placing the nets. Mist netsare set as close to the ground as possible. Nets 18m in length are preferred(the fewer nets, the less effort), but 9m and 12m long nets can also be used asneeded. These nets have four shelves and are a small mesh size, suitable forcapturing passerine birds.

iv) The number of nets operated could always be increased to give a big-ger sample, but this would mean more effort spent in clearing lines, setting upand moving nets, and would not leave much time to collect important biologicaldata on the captured birds. The time spent handling each netted bird is obvi-ously a critical factor. Processing very large numbers is usually not feasible fora survey with limited time and people-power.

Suggested monitoring procedurei) This procedure has been used for forest bird monitoring by mist nets

(with simultaneous point counts) in Kenya.ii) For monitoring, one needs to obtain data that can be compared statis-

tically between monitoring sessions. As with the survey, a combination of mistnetting and observation is employed.

iii) The sample unit is the net-line. Six to eight net-lines are operated ineach study area; the more the better, but time is usually a real constraint. Sixnet-lines is probably the minimum for a study area.

iv) Each net-line consists of a straight series of nets, continuous along a

line cut perpendicular to a survey transect (Fig. 7.2). The length of net isadjusted to ensure a sample of at least 30 birds per net-line. Because of differ-ences in understorey bird density, different lengths of nets will be required atdifferent localities. In Kakamega, 66m of net were found to be sufficient; in theMau forests, 102m were needed. The most suitable length requires some pre-vious experience of the area. In any case, all net lines in a study area shouldpreferably be of identical length. Two lines are operated at once, which meansthat they cannot be too far apart. In Kenya, lines have been cut alternately toleft and right, with around 200m between their starting points. The ringingstation is then based halfway between the two lines.

v) Nets are operated on a strict timetable, again for four hours fromdawn onwards. Records are kept of which site each netted bird comes from(via a small piece of paper folded into each bird bag). In Kenya, netters havefound no records of birds moving between sites, suggesting that each line isindeed an independent sample.

Fig. 7.2: Mist net set up line

Recordingi) For each net site, the layout of the nets should be sketched and notes

made of the site location and habitat type and condition.ii) For each netting session, record the date, the start and end time

(when nets were unfurled and furled), and the weather conditions (see Form7.3).

iii) For each bird caught during a netting session, it is essential to recordthe species, ring number and age and sex (if determined). A number of stan-dard biometric measures are normally taken, including wing length, weight andthe status of moult in the primary wing feathers. Additional biometrics, such ashead and tarsus length, secondary feather, tail and body moult, are also oftenrecorded. For detailed studies, it can be useful to record in which net, and inwhich shelf, particular birds were trapped. The easiest way to do this is to writethe information on a small piece of paper when extracting the bird, then to foldthis and place it in the bird bag. When the bird is removed from the bag so isthe paper, and the details are recorded in the ringing book.

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200m

net line

transect

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iv) Some studies involve taking blood for DNA analysis, putting colourbands on the birds’ legs to allow individual identification when resighted, or tak-ing repeated measurements to assess fluctuating asymmetry. All this informa-tion can be recorded in the ringing book as well.

v) Recaptured birds need to be indicated, usually by means of an ‘R’ in acircle by the ring number.

Data analysisAs far as survey work goes, the data from mist netting essentially con-

sists of a list of species and the numbers trapped. These can be used as ameans of assessing relative abundance. Catch rates for individual species canbe compared between species and sites if they are expressed as individualsper 100-metre-net-hours; see Pomeroy (1992) for examples. Within a study,using a standard length of net for the same hours each day simplifies compar-isons. Totals can readily be summed across feeding or nesting guilds.

Species accumulation curves can be drawn using mist net data, plottingthe cumulative number of species against a measure of effort (such as thenumber of mist net sessions, or cumulative metre-net hours).

Advantages/limitationsMist nets are important because currently they are the only method

available to sample birds of the understorey adequately. Mostly using mist nets,Baker and colleagues (unpubl. data) added some 14 species of forest birds tothe Tanzanian list during fieldwork in Kagera Region, Tanzania. Almost none ofthese species had been identified using binoculars, and the presence of manyprobably would have gone undetected without the use of mist nets.

The main disadvantages of using mist nets are that they are expensiveto purchase, demand a high degree of training to use properly, and are verylabour-intensive to use requiring substantial time and effort, especially incutting net-lines and shifting nets.

Although mist nets allow a standardised approach to surveying under-storey birds, they do not sample birds of the mid- and upper canopy. They alsohave a number of biases. Capture rates are strongly affected by the time ofday, as mentioned above, so comparisons should be made cautiously if theapproaches have not been standardised. The type of nets and the way theyare set also affects capture rates. For monitoring, or collecting comparative sur-vey data, nets should be of high quality with plenty of pocket, must be in goodcondition (holes dramatically reduce the number of captures), and set in a con-sistent manner (stretched tight between poles, and just off-taut betweenshelves). The condition of nets should be checked regularly (at least every halfhour, preferably more often) and any damage repaired (mist nets require

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considerable maintenance). Nets do not sample all birds (even small ones) equally. The standard

mist nets also are not suitable for very large, heavy birds, or fast fliers, such aslarge parrots, pigeons, and birds of prey. Any ringer will be aware that somespecies are more catchable than others. Remsen & Good (1996) showed thatsmall changes in bird behaviour, e.g. alterations in foraging height following for-est disturbance, could potentially cause large changes in capture rates. Thisdoes not invalidate the use of mist nets, but means that results must beinterpreted cautiously. It is another good reason for combining mist netting withobservational work, such as timed transects or point counts. Bear in mind,however, that a team of at least four is needed if mist netting is to be combinedwith counting of canopy birds using point counts.

7.3.9. Sound recordingThe use of tape recorders in bird surveys has not yet been developed as

a standard technique in East Africa, but it has many positive aspects (seeParker, 1991, for a discussion). The human ear is notoriously selective andoften screens out sounds. However, the tape recorder documents all soundsdetected by the microphone. Recorded sounds can then be later used to identi-fy birds, just as field notes and diagrams can be compared in field guides.

Recorded sounds can also be amplified and played back in order toattract birds close enough to enable identification. This can be extremely usefulfor surveying and monitoring shy and hard-to-see species, especially whenthese are scarce and call infrequently. It can be used in an ad hoc way(recording and playing back calls of birds you have detected but do not recog-nise) or more systematically (targeted at difficult-to-locate key species).

Small, inexpensive recorders are readily available and can be linked upwith a video-recorder microphone to form a handy, portable system. It is impor-tant to use a directional microphone, and to ensure that the system producesloud enough playback. Though more expensive than tape recorders, mini-discsystems work very well for sound recording. They are light and portable, storesound digitally, and offer the great advantage that you can edit and copy yourmaterial almost effortlessly.

Equipment� high-quality portable tape recorder or mini-disc player� microphone and batteries� blank tapes or mini-discs� recorded tapes/CDs of bird sounds� plastic bag for protecting equipment against moisture

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Site selection, procedure and recordingFor inventory of key species, playback of recordings can be applied in a

systematic way, for instance by playing a recording for a set length of time at aset volume at a particular point. Any responses by the birds within a set timeperiod (and, if appropriate, their distance: see also above) can then be noted.Virani (2000) applied this method to survey Sokoke scops owl, Scops ireneae,though using a small flute rather than a recorder to imitate their whistled calls.

Systematic playback can also be used for monitoring of one or more tar-get species: the exact points where it is carried out (and the exact time andvolume of playback) then remain fixed between surveys.

For inventories of whole bird communities, Parker (1991) makes thefollowing suggestions:

i) Get up well before dawn and be out in the area to be surveyed atleast 15 minutes before first light.

ii) Choose a different spot each morning from which to record, preferablyat areas at least 500m apart, and let the recorder run for 15 minutes or more(depending on the amount of vocal activity). Point the microphone in the direc-tion of louder sounds for at least 60 seconds. Try to record in all directions andfrom the undergrowth up to the canopy. Cover as many types of forest andmicrohabitats as possible.

iii) Find areas where mixed-species flocks are forming at dawn andrecord them for at least 10–15 minutes. Get 5–10 minutes of sounds from anylarge flock found at any time of day. (Note: mixed-species flocks are especiallyconspicuous in South American forests. Not all African forests have manymixed-species flocks, nor are these flocks always very vocal.)

iv) Once a comprehensive collection of recordings has been assembledfor a locality, attempt to obtain additional recordings of different individuals andeach species.

Data analysisJust as for specimens, recordings need to be accurately documented,

and originals or copies deposited in institutions equipped to curate them. SeeForm 3.3 for an example of a data sheet used by the Macauley Library ofNatural Sounds at Cornell University, Ithaca, USA. The recordings can beanalysed with respect to numbers of species, time of calling, season ofcalling etc.

Advantages/limitationsRecordings (within the physical limits of microphones and tapes/mini-

discs) represent a unique way to document avian species diversity. They caneasily be copied and sent to others for research purposes, and also make anexcellent teaching tool.

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The main limitation is how to keep the equipment from being exposed toexcess heat and humidity. Sophisticated recorders and microphones are alsorelatively expensive, but the costs are outweighed by their versatility and thetype of data they are able to collect.

Playback targeted at key species needs to be used sensibly and in a lim-ited way. Birds responding to the tape (or imitated call) do so because theythink they have detected an intruder in their territory. This disrupts their normalactivities. While it is probably not damaging to carry out single surveys, orrepeated monitoring at long intervals, subjecting particular territorial individualsto frequent playback is unethical and to be avoided.

Bird species respond differently to playback. Some call back but staywhere they are; others come toward the observer and either call or investigatesilently; yet others show no obvious response at all. It is important that you testthe technique on the species you want to target before embarking on asystematic playback survey.

Using tape recordings for bird community surveys, as done by Parker, isvery time-consuming: you need to spend at least as long analysing therecording as making it in the first place. Perhaps for this reason the techniquehas rarely been used in Africa.

7.3.10 Territory mappingFor detailed population studies, it is, in theory, possible, but very time-

consuming, to map the territory of individual singing males. These are thenplotted on a map of the study site, and give precise information as to density(e.g. Terborgh et al.,1990).

However, there are many practical difficulties involved. In eastern Africanforests, it is sometimes difficult to detect singing males. Furthermore, breedingseasons are not always as clear cut as in the northern hemisphere, wherethere is strong, clear, seasonal breeding and where males are frequently morevisually and vocally conspicuous. Moyer (1993) provides a comparative studyin which densities of forest birds were estimated using territory-mapping, mistnetting and direct counts of non-territorial birds. He concludes that territorymapping is the most promising method when estimates of territory size andabsolute density of breeding pairs are needed.

7.3.11 Special considerationsForest birds present a number of challenges to surveyors. Remember to

plan carefully and think clearly about the purpose and objective of your survey,as this will determine the information that you need to obtain, and thus the

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methodology that is most appropriate. If you are mainly interested in, for exam-ple, shifts of guilds between different forest types, then it will not matter much ifyou fail to detect certain cryptic or reclusive species; however, if your focus ison population sizes of those species, then that is a different matter.

Ideally, you need to know something about the birds you are looking forbefore you start. For example, many fruit-eating birds congregate at particularfruiting trees. If there are only one or two such trees in your area, a standardtransect-based survey might under- or over-estimate abundance. A bettermethod might be to locate the trees and do a total count of all the frugivoresthat are using them.

Very cryptic and silent birds can sometimes only be censused by mistnetting. Some reclusive species show strong seasonal patterns of singing (e.g.East Coast Akalat, Sheppardia gunningi: Nemeth & Bennun, 2000). Unless youfind out when these times are, you might easily make erroneous comparisonsbetween sites. Nocturnal birds can often be censused by calls at night, butagain frequently show variations during the night, and within and betweenmonths in their calling activity. This is one of the reasons why surveys need tobe standardised; for instance, all census work might be done during the earlyhours of the evening, around full moon, during the dry season.

In tall forests, canopy species can be extremely hard to identify. A tele-scope can often help, but many birds might still be missed. You need to budgetmore time for survey work in tall forests. You should also be careful of compar-ing population density estimates for canopy birds between low and tall forests.Species that fly above the canopy are even more of a problem: they mightneed to be censused using species-specific techniques, such as counts fromraised points. These are especially useful for birds that fly to and from roostseach day, like parrots and hornbills.

In some forests, birds form mixed-species flocks – feeding aggregationsof several, often many, different species that move through the vegetationtogether. Flocks may move very fast and range over large tracts of forest.Where mixed-species flocking is common, survey techniques that cover rela-tively small areas, like point counts, may not work well. With transects or timedspecies-counts, moving rapidly through the forest until you locate a flock maybe the best approach. Distance methods can be difficult to apply for mixed-species flocks. One approach is to try to estimate the distance to the flock cen-tre and calculate the density of flocks, rather than of individual species.

For some scarce species, such as large forest raptors, conventional cen-sus methods may be hard to apply. Where these species have big, conspicu-ous nests, one approach is to locate and count active nests rather thanindividual birds.

151

7.4 Specimen handlingCasualties among mist-netted birds should be very rare if the nets are

properly handled, but they do sometimes occur. Although specimen collectionis not usually a goal of surveys, the value of the casualty is maximised if it canbe collected for a museum. Sometimes it may be necessary to take voucherspecimens (for instance, to confirm species identification or range extension, orif a suspected new taxon is suspected). Specimen preservation is a topic initself, and cannot be covered properly here.

EquipmentIf voucher specimens or net casualties are to be collected, specimen

collecting permits and material are necessary. For wet specimens: � 10% formalin or 70% alcohol (c.5 litres)� container for holding preserved specimens� hypodermic syringe and needle For collecting dry specimens, more elaborate equipment (e.g. dissecting

kit, needles and thread, borax powder) is required. Consult museum personnelor a specialist text on specimen preparation (see Section 4.4).

Procedure and recordingMuseums have traditionally favoured skins of birds, but more are now

realising the value of specimens preserved in fluid (10% formalin or 70% alco-hol), which is a technique much more suited to the non-specialist. After wash-ing the bird with soapy water to reduce the water repellency of the feathers, itis immersed in 10% formalin of at least three times the volume of the bird.

A label on waterproof paper, with a numbered code for the specimen,should be attached to the left tarsus. See Chapter 4 (on small mammals) foradditional information.

Before preserving the specimen, record biometrics and other information,including soft-part colours (see Fig. 7.4), on the specimen record form (Form7.4), or in a hardback book. If the specimen is dissected before preservation, itis important to note the sex and the stomach contents. Specimens are veryvaluable and it is worth recording as much information on each one aspossible.

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Fig. 7.3: Standard measurements for birds

7.5 Health and safetyVery little work seems to have been done on the potential risk to investi-

gators of birds as regards disease transmission, either direct or by arthropodtransmission. Birds do carry ectoparasites such as fleas, mites, and ticks, andthe latter are known to harbour tick-borne diseases that affect humans. It isprudent for those handling birds to avoid their ectoparasites and to wear surgi-cal gloves and a mask when dissecting specimens and/or preparing studyskins. After handling birds during mist netting and ringing, make sure you washyour hands thoroughly before eating or drinking.

Bats sometimes become caught in mist nets and need to be carefullyfreed. Follow the advice given in Chapter 4 on handling small mammals.

7.6 ConclusionsThe following section is adapted from Bennun & Fanshawe (1998, p.16)

and summarises the advice given above on choosing the most appropriatemethod:

Choose your methodology carefully. For most survey and monitoringwork, only relative abundance measures are required. Distance-sampling usingvariable-width methods (Buckland et al., 1993) is difficult, demanding, and gen-erally only useful for specialised purposes. Because density estimates can becalculated for only the most common species, compiling data for guilds or for-est-dependence categories is difficult. These methods do have the greatadvantage that they take into account the relative ease or difficulty of detectingbirds in particular vegetation types. If bird calls are used in conjunction withsightings, the problem of visual detectability is diminished. Also, if there are bigenough changes in vegetation between sites or monitoring visits to greatlyaffect detectability, it is likely that changes in the bird community will be suffi-ciently large to be picked up with a simple method.

153

Traditional transects can be difficult to place in forests. Timed species-counts, which do not depend on a straight-line route, are one solution, but theyhave substantial disadvantages too. Some of these can be overcome by simplemodification. For comparative survey and monitoring, however, the biggestdrawback concerns the calculated abundance indices, which are not arithmeti-cally tractable – therefore, one cannot simply calculate overall indices for, say,feeding guilds. Timed transects have been tested in several Kenyan forests,and combine the flexibility of timed species-counts with the additive indices of astandard, fixed-width transect.

All of these visual/aural methods work best for canopy and mid-levelbirds. For undergrowth species, standardised mist netting is appropriate forsurvey and monitoring work, although it is labour-intensive and time-consum-ing. By confining point counts and timed transects to birds above a certain level(3m has been used in Kenyan forests), it is possible to differentiate under-growth and higher-level birds. As the results of these studies show, bird com-munity changes can be different at these two levels. This is to be expected,given that structural change after logging can affect high- and low-levelvegetation in very dissimilar ways.

154

7.7 ReferencesAllport, G.A., Ausden, M.J., Fishpool, L.D.C., Hayman, P.V., Robertson, P.A. & Wood, P. (1996).Identification of Illadopsis spp. in the Upper Guinea forest. Bull. Afr. Bird Club 3: 26–30.

Barlow, C., Wacher, T. & Disley, T. (1997). A Field Guide to the Birds of the Gambia and Senegal.Pica Press, London, UK.

Bennun, L.A. (1994). Identification first aid... Kakamega greenbuls. Kenya Birds 2(2): 48–52.

Bennun, L.A. (1999). Threatened birds and rural communities: Balancing the equation. In: Proc. 22Int. Ornithol. Congr., Durban: pp 1546–1555 (Ed. by N.J. Adams & R.H. Slotow). BirdLife SouthAfrica, Johannesburg.

Bennun, L.A. (2000). Monitoring bird populations in Africa: an overview. Ostrich 71: 214–215.

Bennun, L.A. (2001). Long-term monitoring and conservation of tropical wetlands: high ideals andharsh realities. Hydrobiologia. 458: 9–19.

Bennun, L. & Fanshawe, J. (1998). Using forest birds to evaluate forest management: an EastAfrican perspective. In: African Rainforests and the Conservation of Biodiversity, pp. 10–22 (Ed. byS. Doolan). Earthwatch Europe, Oxford, UK.

Bennun, L. & Njoroge, P. (1999). Important Bird Areas in Kenya. East Africa Natural HistorySociety, Nairobi.

Bennun, L.A. & Waiyaki, E.M. (1993). Using timed species-counts to compare avifaunas in the MauForests, south-west Kenya (summary only). Proc. Pan-Afr. Ornith. Congr. 8: 366.

Bennun, L., Dranzoa, C. & Pomeroy, D. (1996). The forest birds of Kenya and Uganda. J. E. Afr.Nat. Hist. 85: 23–48.

Bibby, C., Jones, M. & Marsden, S. (1998). Expedition Field Techniques: Bird Surveys. ExpeditionAdvisory Centre, London, UK.

Bibby, C.J., Hill, D.A., Burgess, N.D. & Mustoe, S. (2000). Bird Census Techniques. 2nd edn.Academic Press, London, UK.

Brooks, T., Lens, L., Barnes, J., Barnes, R., Kihuria, J.K. & Wilder, C. (1998). The conservationstatus of the forest birds of the Taita Hills, Kenya. Bird Cons. Intl 8: 119–139.

Buckland, S.T., Anderson, D.R., Burnham, K.P. & Laake, J.L. (1993). Distance Sampling:Estimating Abundance of Biological Populations. Chapman & Hall, London, UK.

Christy, P. & Clarke, W.V. (1998). Guide des Oiseaux de Sao Tomé et Principe. Ecofac, Gabon.

Colwell, R.K. & Coddington, J.A. (1994). Estimating terrestrial biodiversity through extrapolation.Phil. Trans. Roy. Soc. Lond., Ser. B. 345: 101–118.

Dranzoa, C. (1993). Birds of fragmented forest areas in southern Uganda. Proc. Pan-Afr. Ornith.Congr. 8: 334–340.

Du Plessis, M.A. (1995). The effects of fuelwood removal on the diversity of some cavity-usingbirds and mammals in South Africa. Biol. Cons. 74: 77–82.

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Fanshawe, J.H. (1995). The Effects of Selective Logging on the Bird Community of Arabuko-Sokoke Forest, Kenya. DPhil thesis, University of Oxford, Oxford, UK.

Fjeldså, J. (1999). The impact of human forest disturbance on the endemic avifauna of theUdzungwa Mountains, Tanzania. Bird Conservation International 9: 47–62.

Fry, C.H., Keith, S. & Urban, E.K. (Eds.) (2000). The Birds of Africa. Vol. VI. Academic Press,London, UK.

Furness, R.W. & Greenwood, J.J.D. (Eds.) (1993). Birds as Monitors of Environmental Change.Chapman & Hall, London, UK.

Goldsmith, F.B. (Ed.) (1991). Monitoring for Conservation and Ecology. Chapman & Hall, London,UK.

Hall, J.B. & Rodgers, W.A. (1986). Pole cutting pressure in Tanzanian forests. For. Ecol. Mgmt 14:133–140.

Howard, P.C., Viskanic, P., Davenport, T.R.B., Kigenyi, F.W., Baltzer, M., Dickinson, C.J., Lwanga,J.S., Matthews, R.A. & Balmford, A. (1998). Complementarity and the use of indicator groups forreserve selection in Uganda. Nature 394: 472–475.

Howes, J. & Bakewell, D. (1989). Shorebird Studies Manual. AWB Publication No. 55. AsiaWaterfowl Bureau, Kuala Lumpur, Malaysia.

Kosgey, D.K. (1998). Status and Habitat Choice of Turner’s Eremomela Eremomela turneri (vanSomeren 1920) in South Nandi Forest Reserve, Kenya. MPhil thesis, Moi University, Eldoret,Kenya.

Lens, L. & van Dongen, S. (1999). Evidence for organism-wide asymmetry in five bird species of afragmented afrotropical forest. Proc. R. Soc. Lond., Ser. B 266: 1055–1060.

Lens, L., Galbusera, P., Brooks, T., Waiyaki, E. & Schenk, T. (1998). Highly skewed sex ratios inthe critically endangered Taita Thrush as revealed by CHD genes. Biodiversity & Conservation 7:869–873.

MacKinnon, J. & Phillips, K. (1993). A Field Guide to the Birds of Sumatra, Java and Bali. OxfordUniversity Press, Oxford, UK.

Mackworth-Praed, C.W. & Grant, C.H.B. (1955, 1957). African Handbook of Birds. Series I:Volumes I & II. Birds of Eastern and North Eastern Africa. Longman, London, UK.

Mackworth-Praed, C.W. & Grant, C.H.B. (1962, 1963). African Handbook of Birds. Series II:Volumes I & II. Birds of the Southern Third of Africa. Longman, London, UK.

Mackworth-Praed, C.W. & Grant, C.H.B. (1970, 1973). African Handbook of Birds. Series III:Volumes I & II. Birds of West Central and Western Africa. Longman, London, UK.

Magurran, A. (1988). Ecological Diversity and its Measurement. Croom Helm, London, UK.

Moyer, D.C. (1993). A preliminary trial of territory mapping for estimating bird densities inAfromontane forest. Proc. Pan-Afr. Ornith. Congr. 8: 302–311.

Mulwa, R.K. (2001). The population status and ecology of Taita White-eye Zosterops Poliogastersilvanus (Peters and Loveridge, 1935) in the fragmented forests of Taita Hills, Kenya. MSc thesis,Kenyatta University.

Musila, F. (2001). Status, ecology and conservation of the Sokoke Pipit, Anthus sokokensis, inArabuko-Sokoke Forest, Malindi, Kenya. MSc thesis, Nairobi University.

Nemeth, E. & Bennun, L. (2000). Distribution, habitat selection and behaviour of the East CoastAkalat (Sheppardia gunningi sokokensis) in Kenya and Tanzania. Bird Cons. Intl 10: 115–130.

Newman, K. (2000). Newman’s Birds of Southern Africa. Green Edition. Southern Book Publishers,Halfway House, South Africa.

Newmark, W.D. (1991). Tropical forest fragmentation and the local extinction of understorey birdsin the eastern Usambara Mountains, Tanzania. Conserv. Biol. 5: 67–78.

Newton, I. (1994). The role of nest-sites in limiting the numbers of hole-nesting birds: a review. Biol.Cons. 70: 265–276.

Owiunji, I. (1996). The Long-term Effects of Forest Management on the Bird Community ofBudongo Forest Reserve, Uganda. MSc thesis, Makerere University, Kampala, Uganda.

Owiunji, I. (2000). Changes in avian communities of Budongo Forest Reserve after 70 years ofselective logging. Ostrich 71(1-2): 216–219.

Oyugi, J.O. (1998). Tropical Forest Fragmentation and Avian Population Changes in KakamegaForest, Kenya. MPhil thesis, Moi University, Eldoret, Kenya.

Parker, T.A. III. (1991). On the use of tape recorders in avifaunal surveys. Auk 108: 443–444.

Pomeroy, D. (1992). Counting Birds: a Guide to Assessing Numbers, Biomass and Diversity ofAfrotropical Birds. AWF Technical Handbook Series no. 6. African Wildlife Foundation, Nairobi,Kenya.

Pomeroy, D. & Dranzoa, C. (1997). Methods of studying the distribution, diversity and abundanceof birds in East Africa – some quantitative approaches. Afr. J. Ecol. 35: 110–123.

Pomeroy, D.E. & Tengecho, B. (1986). Studies of birds in a semi-arid area of Kenya. III – The useof ‘timed species-counts’ for studying regional avifaunas. J. Trop. Ecol. 2: 231–247.

Remsen J.V. Jr. & Good, D.A. (1996). Misuse of data from mist net captures to assess relativeabundance in bird populations. Auk 113: 381–398.

Serle, W. & Morel, G. (1992). A Field Guide to the Birds of West Africa. Collins, London, UK.

Sinclair, I., Hockey, P. & Tarboton, W. (1997). SASOL Birds of Southern Africa. 2nd edition. StruikNew Holland, Cape Town, South Africa.

Stattersfield, A.J., Crosby, M.J., Long, A.J. & Wege, D.C. (1998). Endemic Bird Areas of the World:Priorities for Biodiversity Conservation. BirdLife Conservation Series no. 7. BirdLife International,Cambridge, UK.

Stevenson, T. & Fanshawe, J. (2001). A Field Guide to Birds in East Africa. T & AD Poyser,London, UK.

Stork, N.E. & Samways, M.J. (1995). Inventorying and monitoring. In: V.E. Heywood (Ed.) GlobalBiodiversity Assessment, pp. 457–543. UNEP and Cambridge University Press, Cambridge, UK.

Terborgh, J., Robinson, S.K., Parker, III, T.A., Munn, C.A. & Pierpont, N. (1990). Structure andorganisation of an Amazonian forest bird community. Ecol. Monogr. 60: 213–238.

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Thirgood, S.J. & Heath, M.F. (1994). Global patterns of endemism and the conservation of biodiver-sity. In: Systematics and Conservation Evaluation, pp, 207–227. (Eds. P.L. Forey, C.J. Humphriesand R.L. Vane-Wright). Clarendon Press, Oxford, UK.

Tomas Vives, P. (Ed.) 1996. Monitoring Mediterranean Wetlands: A Methodological Guide. MedWetPublication. Wetlands International, Slimbridge, UK and ICN, Lisbon, Portugal.

Turner, D.A. & Zimmerman, D.A. (1979). Field identification of Kenya greenbuls. Scopus 3: 33–47.

Tye, A. (1993). Forest and bird conservation in the East Usambara Mountains, north-east Tanzania.Proc. Pan-Afr. Ornith. Congr. 8: 287–292.

Van Perlo, B. (1996). Collins Illustrated Checklist: Birds of Eastern Africa. Harper Collins, London,UK.

Van Perlo, B. (1999). Collins Illustrated Checklist: Birds of Southern Africa. Harper Collins, London,UK.

Virani, M. (2000). Distribution and population size of the Sokoke Scops Owl Otus ireneae in theArabuko-Sokoke Forest, Kenya. In R.D. Chancellor & B.-U. Myberg (eds), Raptors at Risk.Proceedings of the Fifth World Conference on Birds of Prey and Owls. (Midrand, South Africa, 4–11August 1998), pp. 795–801. Hancock House, Surrey, Canada.

Williams, J.G. & Arlott, N. (1980). A Field Guide to the Birds of East Africa. Collins, London, UK.

Zimmerman, D.A., Turner, D.A. & Pearson, D.J. (1996). Birds of Kenya and Northern Tanzania.Princeton University Press, Princeton, NJ, USA.

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158

Form 7.1: Timed Species-count Records for Forest Birds

Surveyor: Field sheet ref: Date:(total observers): (dd/mm/yy)

Address:

Survey site: Altitude: Aspect:

Latitude: Longitude: UTM (if available):

Vegetation: Human disturbance:

Season: Weather: Lunar phase: Temperature:

Start time: End time: Other:

Time Species Within 25m? Above 3m? Cue Score

Cue = H (heard) or S (seen)

Form 7.2: Bird Recording Sheet for Transect Counts

Surveyor: Field sheet ref: Date:(total observers): (dd/mm/yy)

Address:

Survey site: Altitude: Aspect:

Latitude: Longitude: UTM (if available):

Vegetation: Human disturbance:

Season: Weather: Lunar phase: Temperature:

Transect length: Start time: End length:

Other:

Time Species No. of birds Additional observations:in groups

Write a description on the back of the sheet (noting things such as general size and colour, beakcolour and shape, etc.) for any species you cannot identify with confidence. This can be used later forcomparison with illustrations and descriptions in standard reference works.

159

160

Form

7.3

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161

Form 7.4: Specimen Records: birdsSpecimen reference number: Collection accession number1:

Collector: Date: Time:(dd/mm/yy)

Address:

Collecting site: Altitude:

Latitude: Longitude: Slope:

Additional notes:

Species: Sex: Age:

Ectoparasites: Endoparasites:

Measurements: Soft part coloursWing (mm) Tarsus (mm) Bill (mm) Iris Bill Tarsus Foot

Other:

Moult:

Tissue sample(s) preserved: Blood sample(s) preserved:

Stomach contents:Component: Percentage:

Remarks/Other

1 To be filled in by Museum

Published by Earthwatch57 Woodstock Road, Oxford, OX2 6HJ, UK

Tel: +44 (0)1865 318825, Fax: +44 (0)1865 311383, Email: [email protected]/europe

Registered Charity 327017

ISBN No. 0-9538179-4-6

Publication of this manual has been made possible through a generous donation from Rio Tinto plc

Responsible forest management requires accurate information about a

broad range of species. However, time is too short, and resources too

few, for all forest areas to be considered by specialist survey teams.

This manual provides an overview of the methods which can be used to

gather information. It is designed to be carried into the field to guide

survey work, and enable the user to consider the full range of

vertebrates, excluding fish, found in African forests. It also explains the

basic techniques and basic standards needed for the development of

essential inventory and monitoring programmes.

The manual is particularly aimed at:

• people carrying out short reconnaissance surveys and expeditions;

• undergraduate and graduate students carrying out project and

thesis work;

• research departments of forest, wildlife and national parks

departments;

• forest and wildlife managers and technicians with responsibility for

monitoring biodiversity.