Assessing Sites for Invertebrates

Assessing Sites for Invertebrates

Invertebrates are by far the most biodiverse organisms in our ecosystems but receive proportionately little legal protection or conservation priority when compared to more widely-studied groups such as mammals, birds, amphibians and reptiles.

The few invertebrates that are afforded a high level of legal protection in the UK tend to be rare, limited to specific (often scarce or fragmented) habitats and have a restricted range. Many more invertebrate species are material considerations of the planning process under the provisions of the NERC Act (2006), the Nature Conservation (Scotland) Act (2004) and the Wildlife and Natural Environment Act (2011) respectively; however these mostly include relatively common and widespread species, albeit many of which have been subject to range contractions or considerable declines.

Consultee expectations with regard to level of consideration given to these invertebrates in planning applications is variable, but obtaining the advice of an invertebrate specialist (entomologist) can reduce and contextualise the risk to a planning consent posed by invertebrates, and inform the approach to survey and assessment.

Deriving a Proportionate Approach

Available literature is not very helpful in guiding non-entomologists in determining a robust, defensible but proportionate approach to invertebrate survey. Guidance from Natural England(1) encourages ecologists to seek the advice and guidance of an entomologist at every stage of project evolution, including during initial site scoping surveys, rather than to attempt to make even a preliminary assessment of a site’s potential to support important invertebrate assemblages themselves. In practice, this approach would be impractical and costly for clients if adopted for every site, and an initial filter is needed. Conversely, the numerous more detailed documents on the subject(2) (3), which could be reviewed in order to determine a site-specific approach, are most easily interpreted by specialists.

The latest standing advice from Natural England (last updated in August 2015)(4) has a narrow focus. It is based around the licence requirements of the three native invertebrate species strictly protected by European law (large blue butterfly, Fisher’s estuarine moth and little ramshorn whirlpool snail) and the small number of terrestrial and freshwater invertebrates that receive some protection under Schedule 5 of the Wildlife and Countryside Act 1981 (as amended). In reality, an ecologist is unlikely to encounter most of these species in the majority of sites brought forward for development; there is a far greater possibility that any given site will support one of the hundreds of Priority species(5) or scarce and threatened species(6) present in the UK. These are mentioned in the standing advice, but the message is confusing. For example, Natural England rightly identifies that ‘European Protected Species, Schedule 5 invertebrates and S41 Priority invertebrate species are the protected and priority invertebrates that need to be taken into account in planning decisions,’ but go on to say that surveys and impact assessment of protected species should be undertaken where their distribution and historical records suggest their presence. Priority species are only subsequently mentioned under the heading of mitigation and compensation.

At present, due to the lack of clarity of some guidance documents and the complexity of others, deriving a proportionate approach to invertebrate survey and assessment is complicated, and heavily reliant on receiving good advice from a suitably experienced consultant. In some cases, particularly for developments affecting brownfield and wetland habitats, understanding the effects of the proposals on invertebrates can be a key issue in obtaining consent. Engaging an entomologist early in the process will help identify appropriate levels of survey, mitigation and enhancement; and where necessary, compensation.

Forthcoming Guidance: Plugging the Gap?

There is a clear need for guidance to be produced to help ecologists without specialist entomological expertise identify key habitats and features likely to support important invertebrate assemblages. This would also allow Priority habitats and features important for invertebrates (examples include veteran trees, open mosaic habitat on previously developed land, riverine shingle deposits and ponds) to be identified at an early stage, just as important amphibian, reptile or bat habitats are. The results of the preliminary assessment would then determine the need for more targeted surveys to be completed by an entomologist. Some general guidance on appropriate methods for invertebrate surveys within guidance would also be beneficial and allow ecologists to advise their clients appropriately with regard to timing and indicative cost of work.

The Chartered Institute of Ecology and Environmental Management, in conjunction with Buglife (the Invertebrate Conservation Trust) are planning to publish such a guidance document(7). The aim of this guidance will be to improve the quality and consistency of invertebrate survey amongst UK ecology professionals. For a number of years BSG Ecology has been using an adapted version of the proforma on which it is suggested the guidance may be based(8). This helps our non-entomologist ecologists identify and interpret potentially important invertebrate features.

We are pleased to have been involved in the consultation process for the proposed guidance document and look forward to its publication. It is hoped that this will bring greater clarity on how to approach site assessment for invertebrates, the circumstances in which survey work is required, typical survey methods and the levels of effort required to sample key invertebrate groups.

The BSG Ecology Invertebrate Team

BSG Ecology can provide a complete consultancy service with regard to invertebrates, including site appraisal, survey, species determination, impact assessment, and advice concerning mitigation and compensation strategies that are tailored to individual projects. For further details please contact Dr Jim Fairclough.


Top photograph by Dr. Jim Fairclough : Roman Snail – Listed on Schedule 5 of the Wildlife and Countryside Act 1981 (as amended) for England and Wales 


(1) English Nature (2005) Organising Surveys to Determine Site Quality for Invertebrates: A Framework Guide for Ecologists. English Nature, Peterborough.

(2) – (accessed January 2016)

(3) -(accessed January 2016)

(4) (accessed March 2016)

(5) In England, Scotland, Wales and Northern Ireland, as listed under Section 41 (England) and Section 42 (Wales) of the Natural Environment and Rural Communities (NERC) Act 2006, Section 2(4) of the Nature Conservation (Scotland) Act 2004, and Section 3(1) of the Wildlife and Natural Environment Act (Northern Ireland) 2011, respectively.

(6) (accessed January 2016)

(7) CIEEM (2015) Proposed New Guidance for Commissioning Terrestrial Invertebrate Surveys – A Call for Feedback. In Practice, 88: 43-46.

(8) Dobson, J. R. (March 2010). A Methodology for the Rapid Preliminary Assessment of Invertebrate Habitat Quality Potential, in the course of Extended Phase I Habitat Survey. Version 1.0. Unpublished Consultation Draft.


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