organising surveys to determine site quality for invertebrates

Organising surveys todetermine site quality

for invertebratesA framework guide for ecologists

working towards Natural Englandfor people, places and nature

3Organising surveys to determine site quality for invertebrates

This leaflet is a guide for

ecologists and other

professionals who aim to use

the services of a specialist to

determine the invertebrate

interest of a site. It should be

particularly useful for Local

Government Ecologists, Agency

Staff and conservation bodies.

Although surveys are often

required by the planning

regulations, you may wish to

consider commissioning a

survey for other reasons, for

example as part of biodiversity

enhancement work.

The planning system: whenshould you ask for aninvertebrate survey?

The Government’s objective toconserve biodiversity as an integralpart of sustainable developmentforms a key strand of draft PlanningPolicy Statement 9.

Biodiversity is a material planningconsideration, and planningdecisions must take account ofnature conservation interests,including invertebrates.

Where a proposed development islikely to impact upon biodiversity,the planning system will oftenrequire the developer to carry out asurvey of the biodiversity interest ofa site. Planning decisions must takeaccount of the results of such surveysand seek to avoid significant harm tobiodiversity. Where some impact onbiodiversity is inevitable it should bemitigated, or compensated, bymodifying the design of adevelopment, by attachingappropriate conditions, or by meansof an S106 planning obligation.

A wet flush – an example of good invertebrates habitat. S J Falk

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should be requested from adeveloper, but any site that may have ‘good’ invertebrate interestshould be examined in some way.

Entomologists and invertebratespecialists

The term entomologist specificallyapplies to someone who studies insects.Invertebrate specialists can refer to anyperson who studies insects, spiders,crustaceans (crabs etc), myriapods(centipedes and millipedes), leeches,molluscs (slugs and snails) and anyother groups of animals withoutbackbones, including microscopic ones.

Titles such as ‘Entomologist’ canimply a specialist knowledge thatcovers a wide spectrum of differenttaxonomic groups. This is usuallynot the case. There are over 30,000British invertebrates and to masterthe identification of them all is nearimpossible. Although there are a fewinvertebrate specialists who have avery wide breadth of knowledge,most tend to specialise in one or twotaxonomic groups. With invertebrate

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ureThe degree of protection that can be

given to a site’s biodiversity interestthrough the planning system will depend on its status: legalprotection under the Habitats Directive,notification as an SSSI, or a localprotected designation. If the wildlife ofthe site forms part of a national or localBiodiversity Action Plan, or if there areother legally protected species (underthe Habitats Directive or the Wildlifeand Countryside Act), this will also betaken into account in the determinationof planning applications.

Some developments may require anEnvironmental Impact Assessment(EIA) under the Town and CountryPlanning Regulations 1999, England and Wales. Where therequirement for an EIA isdiscretionary under the Regulations,the environmental sensitivity of aproposal is often a deciding factor.An assessment of the impacts onbiodiversity should form part of anEIA and the process should identifyopportunities to enhance biodiversityand minimise harm.

Where a formal EIA is not justified,developers should be encouraged tocarry out an ecological appraisal tounderstand the impacts of thedevelopment on biodiversity.

A survey of a site’s invertebrateinterest should form part of anywider ecological assessment. There are no hard and fast rulesabout when an invertebrate survey

Organising surveys to determine site quality for invertebrates

diversity being so huge, it is only by focusing on particular groups that any expertise can be fostered.Therefore, it is far more likely toencounter a ‘Lepidopterist’,‘Dipterist’, ‘Coleopterist’ or an‘Arachnologist’ who study moths and butterflies, true flies, beetles or spiders respectively.

Expertise can also be based oncommunity types. For example,some invertebrate specialists focus on wetlands, or just those aquaticspecies within wetlands; others mayhave expertise solely in herb-dominated systems, such asgrasslands, heathlands and dunes. In the examples above, the

taxonomic groups covered will varyconsiderably between surveyors.

Where a wide number of taxonomicgroups is to be covered under oneproject, it is not uncommon for morethan one invertebrate specialist to be involved.

5

Opilo mollis – a scarce saproxylic beetle. Roger Key/English Nature

Swallowtail butterfly – a protected species. Roger Key/English Nature

6

Scoping the site

The best way to gauge likelyinvertebrate interest is for aninvertebrate specialist to carry out a scoping visit. Experiencedinvertebrate specialists can have agood eye for a site’s quality withoutnecessarily undertaking a detailedsurvey. Such a visit focuses onhabitat features, using them toestimate the site’s potential forfurther survey. Sites with a variedhabitat structure usually contain agreater invertebrate interest.

Examples include:

• Areas of flower-rich grasslandthat are NOT regularly mown, cut or grazed and are allowed to flower without interruption.These sites do not have to containrare plants to be of interest.Composites, umbellifers, bird’s-foot-trefoil and vetches inadequate numbers can be of greatvalue as nectar and pollen

sources, and many scarce plant-eating (phytophagous) insects usesurprisingly common foodplants(but sometimes under veryspecific circumstances).

• Areas of early successionalhabitat, particularly on free-draining substrata such aschalk, sand, gravel and rock.These areas, when adjacent toother habitat types (such aswasteland, scrub and wetlands),can be especially good. They areoften used for nesting and sunningspots, and are the focal point formany active, heat-loving(thermophilic) species. (Note thatformer industrial or derelict‘brownfield’ sites may displaymany such features).

• Wetland, such as damp flushes,seepage lines, pools, streams,rivers, wet woodland and coastal habitats. Many rarespecies prefer seasonally-floodedareas as opposed to permanentwater bodies and the value of such habitats should not beunderestimated.

• Scrubland and scrubby grassland,particularly where this forms amosaic with another habitat (suchas flower-rich grassland,woodland or wetland) rather thanoccurring as one distinct block.Scrub provides nesting areas,perches and shelter, as well asproviding food for many species.

A malaise trap. Roger Key/English Nature

Organising surveys to determine site quality for invertebrates

• Mature and veteran trees can also be of high value forinvertebrates, especially wherethese from part of a network oftrees within the wider countryside.Specimens that are in middle tolater stages of decay (a naturalprocess), with hollowed trunk, arethe most valuable to invertebrates.Such trees can occur alonghedgerows, within parklands,orchards, wood-pasture,woodlands and in commercialplantations. Open-grown treesand those in partial shade are ofhigher value for invertebratesbecause they are often betterdeveloped and of a larger sizethan those within a deep canopy.

7

Survey methodology

A competent, experiencedinvertebrate specialist can be left todefine their own methodologies andthe choice of target taxa that willprove most useful in determining asite’s quality. There may beinstances where a survey requires a specific technique (such asrepeating a trapping method as partof long-standing monitoring of thesite to make comparisons with othersites or historical records) but, in themain, an experienced invertebratespecialist will be best placed todecide what needs to be done.Collecting aquatic samples. N Mott

Early successional habitat in a sand quarry. RogerKey/English Nature

If a scoping visit hasdetermined that a site haspotential interest then it mightbe appropriate to follow upwith a full survey. Thefollowing sections deal withthe various issues of setting upand running such a survey.

8

the scope of this document to gointo further detail, but any survey work should be carried out atappropriate times.

Authoritative identifications and the retention of voucher specimensare also critical. Even highly-experienced invertebrate specialistswill send specimens to other expertsfor verification.

Assessing site quality

The most critical aspect of anysurvey report is to define clearly the quality of the site – this should be stressed as one of the outcomes. In simple terms: how good is it forinvertebrates? Any report thatdoesn’t highlight this has failed in its remit.

Other questions worth asking are: is the site improving or deteriorating?Is it in a state of constant flux? Howresilient is the site in relation todisturbance, site management andnatural succession?

On the other hand, there is a risk that an inexperienced invertebratespecialist might use the wrongmethodology for a site, only collect the groups with which they are most familiar, fail to ask the right questions, or misinterprettheir results. Therefore, beforechoosing a surveyor, seek the advice of local ecological experience in organisations, such as the local wildlife trust, or localrecords centre.

Certain taxonomic groups can only be surveyed within veryspecific timescales. Most speciesbecome more active throughout the spring and summer months, this activity tailing off through the autumn and winter. Manyspecies (bees, for example) havevery specific flight periods, onlybeing ‘on the wing’ when certainplants are in flower. It is beyond

A solitary bee, Megachile sp. Roger Key/English Nature

Exposed riverine sediment. N Mott

A survey should classify a site as oneof the following:

The surveyor should come to theseconclusions by comparing andcontrasting with other sites of similarnature and habitat. For example, asite is of regional importance if itcompares well with other sites within


that region; a site is of countyimportance if it compares well withother sites within that county. Whereuseful data is unavailable, expertopinion must be relied upon instead.

Where a county does not haveinvertebrate data for a wide range ofcomparable sites, it may be feasibleto compare results with other datasetsfrom outside the county. This isparticularly useful when comparingyour site with a site that has alreadybeen assigned a level of importance(see table opposite) and a reason forthis - for example, “this site has anationally important dead woodfauna”. Where there is little or nocomparable data, every effort shouldbe made to undertake further surveywork on four or five comparable sitesin the same region. Extra survey anddata comparison work should beconsidered at the planning stage ofany proposed survey or, if not carriedout, highlighted as an omission.

Where information is inadequate, it is prudent to assume that the site is of high value until proven otherwise.

1 Little / no importance.

2 Local / county importance:would/should qualify underCounty Wildlife SiteGuidelines. Such sites havemerit at the county level andare recognised in theplanning process.

3 Regional importance: a siteclearly of high interest at the regional level althoughnot necessarily outstandingnationally. This categoryincludes examples of speciesgroupings and assemblagesthat may be poorlyrepresented in that region but are perhaps common in other areas.

4 National importance: a sitethat, when compared withothers, is of outstandinginterest at a national level.

5 European importance: onethat has features/assemblagesof international significance.

Direct searching on exposed riverine shingle. N Mott

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Rarity. Possibly the most commonly-used indicator of quality. Sites that support numbers of rare species can be considered as being of high nature conservation importance.

Fidelity. Fidelity measures a species selectivity to certain habitats. Some species have a very high fidelity to specific habitats and are not found elsewhere. Sites that support anumber of species with a high habitat fidelity should be considered of high importance.

Species richness within any given community/assemblage.Species richness of a specificcommunity, even of commonspecies, can infer site quality.Species richness of a particulartaxonomic group, especially incomparison with similar sites, can also infer quality. However, it should be noted that qualitybased on the overall speciesrichness of a site is not necessarilyindicative of quality and is often aresult of the survey methodsemployed – it is not difficult togenerate large lists of common and ubiquitous species! It must also be noted that some invertebrate communities, those in acid mires for example, haveinherently low species-richness.

An example of assessing sitequality:

A chalk quarry contains an earlysuccessional/herb richassemblage mainly of bees,wasps and beetles. Thisassemblage includes 102 speciesof which 33 are local, 15 arenotable and three are Red DataBook (RDB) species.

This information was comparedwith similar sites within thecounty and the quarry was foundto contain a greater speciesrichness, a higher number of rareand scarce species and thelargest concentration ofcalcicolous species. It is at leastof regional importance. Furtheranalysis would be required todetermine whether it was ofnational importance.


Frequently-used statuses for invertebrates in descending order ofrarity (based on post-1970 records):

Unknown: species for which distribution has not been fully determined.These species are often from poorly-studied groups that are difficult toidentify.

Common: species readily recorded at a number of different localitiesthroughout the UK and seemingly well distributed. Can include ubiquitousspecies found in a variety of situations, for example, the seven-spotladybird Coccinella septempunctata, as well as common species requiring amore specific niche, for example, the common cardinal beetle Pyrochroaserraticornis, that lives under bark.

Local: this is a less formal category used to cover species which are notcommon. They may be widespread but restricted to vulnerable habitats.Many are useful indicators of a particular habitat.

Nationally scarce: species estimated to be recorded in 16-100 hectads ofthe National Grid.

Nationally scarce, Category B: recorded in 31-100 hectads of the National Grid,or, for less well-represented groups, between eight and 20 vice-counties.

Nationally scarce, Category A: recorded in 16-30 hectads of the national grid, or, for less well-represented groups, within seven or fewer vice-counties.

Red Data Book RDB3: rare. Estimated to exist in only 15 or fewer hectads.

Red Data Book RDB2: vulnerable. Taxa believed likely to becomeendangered in the near future.

Red Data Book RDB1: endangered. Species which are known or believed to occur as only a single population within one hectad of the National Grid.

Red Data Book RDBI: indeterminate. Taxa considered to be endangered,vulnerable or rare, but where there is not enough information to saywhich of the three categories (RDB1-3) is appropriate.

Red Data Book RDBK: insufficiently known. Taxa that are suspected, butnot definitely known, to belong to one of the above categories.

Critically Endangered (CR)

Endangered (EN)

Vulnerable (VU)

Lower Risk (LR). Split into:

Extremely high risk of extinction

Very high risk of extinction in thenear future

Very high risk of extinction inmedium term

Conservation Dependant (LRcd)

Near Threatened (LRnt)

Nationally Scarce (LRns)

Least Concern (LRlc)

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IUCN categories in descending order of risk

What communities are present?

It is important to list the more valuablecommunities present on a site. Lists of species have their merit but whenthey have not been split into ecologicalassemblages, it is often difficult toassess which aspects of a site are ofgreatest significance. Therefore, anyreport should state the communitiespresent, give some indication of theirlocation on-site and their interest level.

Examples of ecological communities/assemblages for invertebrates:

• dead wood (saproxylic)

• early successional

• aquatic

• brackish

• suites of species associated with certain food-plants.

If a survey is based on the sampling of one (or a few) taxonomic groupsthen it should be noted that, dependingon habitat, some groups are betterindicators of quality than others.

For example: bees and wasps(aculeate Hymenoptera in part) areexcellent indicators of flower-richhabitats, early successional habitatsand ericaceous heathland, but aregenerally poorly represented inwetland habitat and are thus poorindicators of its quality. Beetles aregood indicators for a variety ofhabitats but the families representedin different habitat types vary greatly,for example, rove beetles(Staphylinidae) and ground beetles(Carabidae) are good indicators ofwetlands, while weevils(Curculionidae) and leaf beetles(Chrysomelidae) are well representedin flower-rich and scrubby habitats.


Stag beetle. Stuart Ball

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Species of special interest

As well as describing thecommunities present, there mightalso be instances where a particularspecies is of high enough interest tomerit mention in its own right. These should include:

• UK BAP listed species.

• Schedule 5 species cited in theWildlife & Countryside Act.

• Threatened species. In mostinstances limited to RDB1(endangered) and RDB2(vulnerable) species and the CR,EN and VU categories in theIUCN categories.

Where these species do occur on-site,their locations and the locations ofhabitats suitable for them should benoted.

How long should the surveyand report take?

The time that needs to be allotted to asurvey and subsequent report writingwill depend on a number of factors:the number and type of taxonomicgroups covered, the skill of thesurveyor, the intensity of the surveyand the size of the site. Unforeseenfactors, such as extreme weather,might also play a part.

As a guideline, for an ‘average’ site(between 10 ha and 50 ha) where a

number of groups is being covered,then at least eight days, butpreferably more, should be allotted.This would be broken down as:

• Three to seven days of field work(five to seven hours per day insummer, with less time usuallyneeded in spring and autumn.)

• Three to seven days ofidentification, possibly more fordifficult groups.

• Two to five days of report-writing,usually carried out in winter oncethe field season is finished.

If a surveyor is looking at a numberof different taxonomic groups, then a number of visits over a long period(for example, between March andOctober) may be required. Wheresurveys are more specific (for

High brown fritillary butterfly. Michael Hammett/English Nature


Finance

Where resources are limited, thesurvey should focus on areas andspecies that would yield the mostinterest (do you want a large specieslist from the whole site, or do youjust want to know how important anarea of relict fen is?). Also, giventhat the start of the optimum surveyseason coincides with the start of thefinancial year, it is important to sortout contracts as soon as possible,preferably a few months before thestart of spring.

example, an aquatic survey only orwhere the area of land is small) thenthe survey time can be reduced.Conversely, larger sites will meritmore work. If traps are to be set thenthe time taken to set and empty them,and to sort any catches must also betaken into account.

Certain habitats are more productiveat certain times of the year, forexample, ericaceous heathland whenthe heather blooms in late summer,and grasslands in June and July whenmost plants are in flower.Soft rock cliffs – an example of good habitat for invertebrates. A Jukes

• Ensure boundaries demarkingareas of interest have beenaccurately mapped.

• List factors that may affect sitequality.

What the surveyor will needfrom you:

• Clear instructions on what thesurvey is intending to achieve.

• Maps for use in surveying andsubsequent reporting.

• Any previous records from thesite and other relevant sites.

• The contact details of usefulindividuals and organisations.

• The relevant access permissionsand landowner contacts.

You should also:

• Ensure that the surveyor has madean assessment of any health andsafety issues on site andcompleted the relevant FieldworkRisk Assessment Sheets (thoughin some cases this might be theresponsibility of the Contractor).

• Ensure that the surveyor has been given a reasonable deadline.Most invertebrate specialists willundertake report writing in thewinter, so a mid-winter deadlinewould be reasonable for many.

16

What should be included in areport?

• A description of methodologiesand name of the surveyor andidentifiers.

• List everything, not just the rarespecies. Denote which taxonomicgroups have been targeted.

• List the species in more than one order; alphabetically for non-invertebrate specialists andtaxonomically for invertebratespecialists.

• Provide all data – full scientificname, recorder, location, date andgrid reference.

• Ensure that the site’s quality –including comparisons with othersites – has been properly defined.


Alexander, K.N.A., Drake, M., Lott, D.A & Webb, J.R. 2005. InvertebrateAssemblages on English SSSIs. English Nature Research Report, No. 618. English Nature.

Alexander, K.N.A. 2004. Revision of the index of ecological communityas used for saproxylic beetles. English Nature Research Report, No. 574.English Nature.

Alexander, K.N.A. 2003. A review of the invertebrates associated with lowland calcareous grassland. English Nature Research Report, No. 512. English Nature.

Anon. 1989. Guidelines for Selection of Biological SSSIs. Nature Conservancy Council.

Boyce, D.C. 2002. A review of seepage invertebrates in England. English Nature Research Report, No. 452. English Nature.

Boyce, D.C. 2004. A review of the invertebrates of acid mires. English Nature Research Report, No. 592. English Nature.

Eyre, M.D. & Lott, D.A. 1997. Environment Agency R& D TechnicalReport W11: Invertebrates of Exposed Riverine Sediments. EnvironmentAgency.

Eyre, M.D. & Luff, M.L. 1990. The ground beetle assemblages of Britishgrasslands. Ent. Gaz. 41: 197-208.

Eyre, M.D. & Luff, M.L. 2002. The use of ground beetles (Coleoptera:Carabidae) in conservation assessments of exposed riverine sediments in Scotland and northern England. Journal of Insect Conservation, 6, pp 25-38.

Falk, S.J. 1998b. Individual Species Impact Assessments: A standardisedpresentation technique for describing the impact of developmentproposals on critical invertebrate species. British Journal of Entomologyand Natural History, 11: 19-29.

Further reading

18

Foster, G.N. & Eyre, M.D. 1992. UK Nature Conservation No.1:Classification and Ranking of Water Beetle Communities. Joint NatureConservation Committee.

Fowles, A.P., Alexander, K.N.A. & Key, R.S. 1990. The Saproxylic QualityIndex: evaluating wooded habitats for the conservation of dead-woodColeoptera. Coloepterist 8(3): 121-141, November 1999.

Harding, P.T. & Rose, F. 1988. Pasture-woodlands in Lowland Britain.Abbots Ripton: ITE.

Howe, M. 2003. Coastal Soft Cliffs and their Importance forinvertebrates. British Wildlife 14: 323-331.

Key, R.S. 2000. Bare ground and the conservation of invertebrates.British Wildlife 11: 183-191.

Kirby, P. 1994. Nature Conservancy Council Report No. 89: Habitatfragmentation; species at risk. Nature Conservancy Council.

Lott, D.A. 2003. An annotated list of wetland ground beetles(Carabidae) and rove beetles (Staphylinidae) found in the British Islesincluding a literature review of their ecology. English Nature ResearchReport, No. 488. English Nature.

Speight, M.C.D. & Castella, E. 2001. An approach to interpretation oflists of insects using digitised biological information. Journal of InsectConservation. 5. pp141-144.

Office of the Deputy Prime Minister 2004. Consultation paper onPlanning Policy Statement 9: Biodiversity and Geological Conservation.

Further reading (continued)

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Organising surveys to determine site quality for invertebrates 19

English Nature, the RuralDevelopment Service and theCountryside Agency. Working in partnership to conserve and enhance our landscapes and naturalenvironment, to promote countrysideaccess and recreation as well as public well-being, now and for future generations.

This is one of a range of publicationspublished by: External Relations TeamEnglish NatureNorthminster HousePeterborough PE1 1UA

www.english-nature.org.uk

© English Nature 2005

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Front cover photographs:Top left: Old oak in field margin,Devon. Roger Key/English Nature Bottom left: Chrysis ignita. Roger Key/English NatureMain: Water beetle survey. M Nott

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