ecology of the greater padloper, homopus...

Ecology of the Greater padloper,

Homopus femoralis

Project proposal for a field study 2008−2012

Victor Loehr Update: 13 January 2010

Homopus Research Foundation

Kwikstaartpad 1 3403 ZH IJsselstein

Netherlands [email protected]

Ecology of Homopus femoralis: project proposal

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Contents

Introduction .................................................................................................................. 2

Research aims ............................................................................................................... 2

Materials and methods ................................................................................................... 3

Study area........................................................................................................................................3 Fieldwork episodes ...........................................................................................................................3 Data collecting ..................................................................................................................................3 Temporary removal of tortoises .........................................................................................................4

Planning and permits ..................................................................................................... 4

Budget.......................................................................................................................... 5

Volunteers .................................................................................................................... 5

Collaborators ................................................................................................................ 6

Literature cited ............................................................................................................. 6


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Introduction South Africa harbours the most diverse tortoise fauna on earth. Of the circa 43 tortoise species world-

wide, 13 are found within the South African borders (Boycott & Bourquin 2000; Branch 2007; Fritz & Havaš 2006). Five species occur exclusively in South Africa (Ernst et al. 2000). This gives South Africa an important position in the conservation of tortoises.

Many tortoise species are threatened. The IUCN Red List of Threatened Species lists 17 species as Vulnerable, nine as (Critically) Endangered, and five are already extinct (IUCN 2007). The main threats are probably habitat alteration (i.e., land development, overgrazing, mining, etc.), and collecting for consumption or the pet trade (Turtle Conservation Fund 2002). In recent years, concerns regarding the effects of climate change on tortoise populations have increased, and this threat may be particularly relevant to South Africa (Loehr et al. 2007a, 2007b; Midgley et al. 2001; Rutherford et al. 1999). Until now, South Africa’s tortoises appear to be reasonably safe, with no species listed as Vulnerable and only one listed as Endangered (IUCN 2007). In addition, the South African Red Data Book lists a second species as Rare (Branch 1988). A third taxon listed as Restricted in the South African Red Data Book was invalidated recently (Daniels et al. 2009).

In order to assess and monitor the conservation status of tortoises, and to develop conservation plans for (potentially) threatened species, ecological information is crucial. The rich South African tortoise fauna demands a large investment, but only few species have been studied in detail: Chersina angulata (Henen & Hofmeyr 2003; Hofmeyr 2004; Joshua et al. 2005; Keswick et al. 2006; Lesia et al. 2003; Mann et al. 2006; Ramsay et al. 2002), Stigmochelys pardalis (Douglas & Rall 2006; Mason et al. 1999; McMaster & Downs 2006a; McMaster & Downs 2006b; Milton 1992; Perrin & Campbell 1981; Rall & Fairall 1993; Scantlebury & Minting 2006), and Homopus signatus (Bayoff 1995; Loehr 2002a, 2002b, 2004, 2006; Loehr et al. 2004, 2006a, 2006b, 2007a, 2007b, 2009). Considering the growth of the South African economy (Central Intelligence Agency 2007) and associated pressure on the environment, and predicted climate change (Midgley et al. 2001; Rutherford et al. 1999), additional studies on tortoises are urgently required.

A group of tortoises that is endemic to southern Africa are the Padlopers (genus Homopus), with four

species occurring in South Africa (one entering Lesotho), and one in Namibia (Ernst et al. 2000). They are restricted to specific habitats (e.g., rocky areas; Boycott 1989; Boycott & Bourquin 2000; Loehr 2002b) in relatively small distribution ranges, emphasising their fundamental vulnerability. Ironically, the biologies of Homopus spp. are mostly unknown (Boycott & Bourquin 2000). Only H. signatus has been studied, and H. areolatus is currently under investigation (Henen & Hofmeyr 2003; BT Henen & MD Hofmeyr, personal communication).

The Greater padloper (H. femoralis) occurs in south and south-central South Africa and southern Lesotho, from the Komsberg Mountains in the west to Queenstown in the east, and to the vicinity of Kimberley in the north (Boycott & Bourquin 2000). In this area, it inhabits rocky ridges in mountain and plateau grasslands (Branch 1989). Published information on its ecology is limited to a few notes on hibernation, feeding on sheep faeces, predation by baboons, birds and small carnivores, egg-production and hatching in summer, and egg and hatchling size (Boycott & Bourquin 2000; Branch 1989, 1999; Kuperus & Loehr 2009). There are no specific studies on H. femoralis. Boycott & Bourquin (2000) mention that research is required to establish actual distribution limits, population size and dynamics, and conservation requirements. The current document proposes a field study on H. femoralis.

Research aims The primary aim of the proposed study is to gather and publish ecological information that is relevant

for the long-term conservation of H. femoralis. It will focus on population structure and dynamics, tortoise growth rates, habitat use, activity and movement, diet, and reproduction. Results may simultaneously accommodate an academic interest. Homopus femoralis shares ecological characteristics with other Homopus spp. For example, it inhabits mesic habitats and produces multiple-egg clutches similar to H. areolatus (Boycott & Bourquin 2000), but it is associated with rocky environments similar to H. boulengeri, H. signatus and H. solus (Boycott & Bourquin 2000; Branch 1989). It is unique in being the largest of all Padlopers. Comparing H. femoralis with other Homopus spp. will help explain how the environments of Homopus spp. relate to their different appearances and ecologies (e.g., body size, reproductive strategy). In


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addition, studying a second relatively small, rock-dwelling tortoise, next to H. signatus, will consolidate the understanding of the ecologies of small tortoises that are restricted to rocky habitats. Materials and Methods Study area

In March 2006, I selected a circa 7.7 ha study area near Beaufort-West (Western Cape Province). This area consists of a gently sloping north-westerly facing rocky hill (see photograph). I will map the various microhabitats and elevations in the area by means of GPS/GIS. The study site will also have a permanent transect to quantify annual primary production through vegetation cover and abundance analysis.

Rainfall, temperature, and humidity dataloggers have been placed at the site in March 2006, to accumulate data that might affect the tortoise ecology (e.g., reproduction) in 2008 and thereafter.

Fieldwork episodes

Annual fieldwork is scheduled for December 2008, and for January/February 2010 to 2012, but additional fieldwork may be required in other seasons. Fieldwork episodes will take 2−3 weeks, during which the study area will be methodically inspected for tortoises daily. Initially, inspections will start at 07:00 and stop at 19:00 hrs, but will be shortened or lengthened to include tortoises’ daily activity period.

The number of tortoise sightings per fieldwork episode will be increased by radiotelemetry. In January 2011, I will place radiotransmitters on 10 male and 10 female tortoises, to track them daily. Brief bimonthly fieldwork episodes may follow until February 2012. Simultaneously, these tortoises will be equipped with thermochron iButtons that automatically measure and store shell temperatures at a specified interval.

Data collecting

To facilitate comparisons with data on H. signatus, much of the research protocol will be adopted from an earlier project on this species (e.g., Loehr 2002a, 2002b; Loehr et al. 2007a, 2007b). When a tortoise is encountered, I will take the following records:

• Date and time • Weather conditions (sun; partly clouded; overcast; drizzle; rain; thunderstorm) • Cloud cover (0-25; 25-50; 50-75; 75-100%) • Soil, sun and shade temperature (infrared measurements) • GPS locality • Microhabitat (to be characterised in November 2008) • Sun exposure (full sun; full shade; half shade) • Dorsal cover (percentage) • Type of retreat, when hiding (crevice or shrub; depth of crevice; orientation and concealment

entrance) • Body mass of the tortoise • Shell dimensions (straight carapace length; maximum shell width, at xth marginal; shell width

at the 6th to 7th marginal; maximum shell height, at xth vertebral; shell height at the 4th to 5th vertebral; straight plastron length; size of the anal gap)

• Scute aberrations • Group (male; female; juvenile) • Activity (basking; walking; hiding; feeding; combat; mating)


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• Carapace, plastron (infrared) and cloacal (probe) temperature; recordings of cloacal temperatures will stop once correlations between carapace, plastron and cloacal temperatures will have been established

The following will be collected when processing a tortoise:

• Faeces (to be deposited at the University of the Western Cape for faecal analysis) • Urine (to be deposited at the University of the Western Cape for health analysis) • Blood (to be deposited at the University of the Western Cape for health analysis) • Plant sample (when a tortoise was feeding, to be deposited dry at Compton Herbarium)

Before releasing tortoises at the site of capture, they will be notched (Honegger 1979) and digitally

photographed (plastron and carapace) for future identification. Temporary removal of tortoises

In some cases, it will be essential to remove tortoises temporarily (< 48 hrs) from their habitat, and to move them to Beaufort West (Western Cape Province):

• Placing radiotransmitters (January 2011) • Placing thermochron iButtons (January 2011) • Radiographing and ultrasound scanning females to determine their reproductive status (all

fieldwork episodes) Planning and Permits

This proposed study would run from December 2008 until December 2012, preliminarily including four fieldwork episodes. Table 1 provides dates and expected permit requirements for activities. I will update this schedule annually, to submit it to CapeNature in order to evaluate permit requirements for the next fieldwork. Table 1. Planning and permits. Fieldwork episode Activities Permit required December 2008 • Mapping microhabitats and elevations

• Setting up permanent transect • Vegetation analysis • Locating and handling tortoises in the field

o Transporting faeces, urine and blood to UWC o Collecting food plant samples (1 per species) o Transporting food plant samples to Compton Herbarium

• Temporarily removing 20 female tortoises for X-raying o Radiographing max. 20 females

No No No Yes Yes Yes Yes Yes Yes

February 2010 • Vegetation analysis • Locating and handling tortoises in the field

o Transporting faeces, urine and blood to UWC o Collecting food plant samples (1 per species) o Transporting food plant samples to Compton Herbarium

• Temporarily removing 30 female tortoises for X-raying o Radiographing max. 30 females o Ultrasounding max. 30 females

No Yes Yes Yes Yes Yes Yes Yes


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Fieldwork episode Activities Permit required January 2011 • Vegetation analysis

• Locating and handling tortoises in the field o Transporting faeces, urine and blood to UWC o Collecting food plant samples (1 per species) o Transporting food plant samples to Compton Herbarium


• Temporarily removing 10 male and 10 female tortoises o Equipping 20 tortoises with radiotransmitters o Equipping 20 tortoises with iButtons

No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes

Jan 2011−Feb 2012 • Fieldwork episodes and activities yet to be determined Not yet known February 2012 • Vegetation analysis

• Locating and handling tortoises in the field o Transporting faeces, urine and blood to UWC o Collecting food plant samples (1 per species) o Transporting food plant samples to Compton Herbarium


• Temporarily removing 10 male and 10 female tortoises o Removing radiotransmitters from 20 tortoises o Removing iButtons from 20 tortoises

No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes

Gathered data will be processed between fieldwork episodes and in the end of the study. I will submit

manuscripts for publication in international, peer-reviewed journals. The publishing process may take up to several years from December 2012. Budget

Costs for this study will be low, for two reasons: (1) most of the research materials are already available at the Homopus Research Foundation, and (2) volunteers will provide the required capacity (including management). The remaining costs are listed in Table 2, and are totals for the entire project (2008-2012).

Table 2. Required budget and sources. Item Costs (€ / R1) Source of funding International travel expenses 11,000 / 111,099 Volunteers National travel expenses 4,000 / 40,406 Volunteers Housing 4,000 / 40,406 Volunteers Radiotransmitters 2,000 / 20,203 Homopus Research Foundation2 Rebatterying existing transmitters 1,000 / 10,102 Homopus Research Foundation2 Identification plant species Compton 300 / 3,030 Homopus Research Foundation2 Radiography 600 / 6,060 Homopus Research Foundation2 Various field materials 500 / 5,051 Homopus Research Foundation2 Literature 100 / 1,010 Homopus Research Foundation2 Publication manuscripts 100 / 1,010 Homopus Research Foundation2 Unexpected - 10% of budget 2,360 / 23,839 Homopus Research Foundation2 Total 25,960 / 262,225 1 Exchange rate 31 December 2007 2 The Homopus Research Foundation will attempt to acquire funding at European reptile societies, zoos, and

foundations sponsoring herpetological research

Volunteers

The previous work on H. signatus has benefited from volunteer assistance in the field. Most volunteers were private tortoise keepers or zoo staff from overseas. There are both positive and negative aspects that


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need consideration. Positively, volunteers provide expert capacity (i.e., they are familiar with the biology of tortoises and often have field experience), allowing to locate reasonable numbers of tortoises in a short while, at virtually no costs. In addition, they may provide additional funding. Interestingly, several volunteers who have participated in H. signatus fieldwork continued to contribute financially later. The most important benefit of working with volunteers probably is increased tortoise conservation awareness. Without exception, volunteers had a much better understanding of factors that threaten the survival of tortoises in the wild after their participation. Back home, this awareness transfers to other tortoise keepers, via lectures and informal contacts. Illegal trade in poached tortoises is a continuing problem, and increasing awareness may be an effective way to help preventing it. Either because tortoise keepers no longer find it acceptable to purchase (potentially) illegal specimens, or because there is social pressure illegitimating purchasing such tortoises.

Negatively, volunteer participation implies the risk that tortoise localities become public knowledge, increasing the risk of poaching. To reduce this risk, all volunteers are explicitly asked not to share with others localities, or photographs that contain landmarks that may direct others to the sites. In five years of research on H. signatus, there has been no evidence of localities shared. Considering positive and negative aspects, I strongly feel that the advantages outweigh disadvantages.

Collaborators

In this study, several organisations will collaborate:

University of the Western Cape (prof. MD Hofmeyr) Throughout the project, plans and results will be communicated and discussed with the Chelonian

Biodiversity and Conservation programme of the University of the Western Cape to ensure that the project will complement the programme’s efforts. Furthermore, the University of the Western Cape will provide expertise and equipment for conducting ultrasound measurements, and possibly capacity to gather field data. This project will collect urine and blood samples for donation to the university for tortoise health analysis.

CapeNature (Mrs. D Kleinhans, Dr. EHW Baard)

CapeNature is the competent authority for wildlife in the Western Cape Province. Since the study area is located in the Western Cape, CapeNature will advise and consider the permit applications for this project.

Compton Herbarium

Identifications of food plant samples will be done by Compton Herbarium, through the standard service offered by this institute. Compton Herbarium is specialised in South African taxa, and samples deposited at the herbarium will remain in their country of origin, might the herbarium decide to include samples in its collection.

Literature cited Bayoff, N. 1995. Observations and morphometric data on the Namaqualand speckled tortoise, Homopus

signatus signatus (Gmelin, 1789), in South Africa. Chelonian Conservation and Biology 1: 215-220. Boycott, R.C. 1989. Homopus boulengeri, Karoo padloper; Boulenger's padloper; Red padloper; Biltong

tortoise (English), Karooskilpadjie; Rooiskilpadjie; Donderweerskilpad; Biltongskilpad (Afrikaans). In: Swingland, I.R., Klemens, M.W., IUCN/SSC Tortoise and Freshwater Turtle Specialist Group & The Durell Institute of Conservation and Ecology (eds.). The conservation biology of tortoises: Occasional papers of the IUCN Species Survival Commission no. 5. IUCN, Gland, Switzerland. Pages 78-79.

Boycott R. & Bourquin, O. 2000. The southern African tortoise book: a guide to southern African tortoises, terrapins and turtles. Privately printed, Hilton, South Africa.

Branch, W. 1989. Homopus femoralis, Greater padloper; Karoo tortoise (English); Vlakskilpad; Bergskilpadjie, Groter padloper (Afrikaans). In: Swingland, I.R., Klemens, M.W., IUCN/SSC Tortoise and Freshwater Turtle Specialist Group & The Durell Institute of Conservation and Ecology (eds.). The conservation biology of tortoises: Occasional papers of the IUCN Species Survival Commission no. 5. IUCN, Gland, Switzerland. Pages 80-81.


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Branch, W.R. 1988. South African Red Data Book - Reptiles and Amphibians. South African National Scientific Programmes Report 151: 1-241.

Branch, W.R. 1999. Homopus femoralis, greater padloper, egg and clutch size. African Herp News 30: 28-29.

Branch, W.R. 2007. A new species of tortoise of the genus Homopus (Chelonia: Testudinidae) from southern Namibia. African Journal of Herpetology 56: 1-21.

Central Intelligence Agency. 2007. The world factbook 2007. Central Intelligence Agency, Washington, D.C.

Daniels, S.R., Hofmeyr, M.D., Henen, B.T. & Baard, E.H.W. 2009. Systematics and phylogeography of a threatened tortoise, the speckled padloper. Animal Conservation, doi:10.1111/j .1469-1795.2009.00 323.x.

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Keswick, T., Henen, B.T. & Hofmeyr, M.D. 2006. Sexual disparity in activity patterns and time budgets of angulate tortoises (Chersina angulata) on Dassen Island, South Africa. African Zoology 41: 224-233.

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Loehr, V.J.T., Henen, B.T. & Hofmeyr, M.D. 2004. Reproduction of the smallest tortoise, the Namaqualand speckled padloper, Homopus signatus signatus. Herpetologica 60: 444-454.

Loehr, V.J.T., Henen, B.T. & Hofmeyr, M.D. 2006a. Shell characteristics and sexual dimorphism in the Namaqualand speckled padloper, Homopus signatus signatus. African Journal of Herpetology 55: 1-11.

Loehr, V.J.T., Henen, B.T. & Hofmeyr, M.D. 2006b. Tick infestations in the Namaqualand speckled padloper, Homopus signatus signatus (Gmelin, 1789). African Zoology 41: 170-177.

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Loehr, V.J.T., Hofmeyr, M.D. & Henen, B.T. 2009. Small and sensitive to drought: consequences of aridification to the conservation of Homopus signatus signatus. African Journal of Herpetology 58: 116-125.

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