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Guide to Ecological Surveys and Their Purpose

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When assessing planning applications, the relevant authority will need to consider whether the project accords with nature conservation legislation and planning policy. For development projects which do not require a planning application to be made (such as permitted development or exempted development), the project will need to comply with nature conservation legislation.

CIEEM recommends that the Ecological Impact Assessment (EcIA) process is used to present an assessment of the likely significant ecological effects of any development project which could affect biodiversity, irrespective of the scale of the project. See CIEEM’s Guidelines for Ecological Impact Assessment.

Any EcIA should be based on robust survey data. Surveys should be undertaken following relevant good practice guidance; any departures from such guidance should be justified. The starting point for any site-based assessment is normally a desk study and a walkover survey, such as an Extended Phase 1 Habitat Survey in the UK (based on JNCC, 2010)1 or a walkover survey plus a habitat survey using A Guide to Habitats in Ireland (Fossitt, 2000)2 in Ireland. This is referred to as a Preliminary Ecological Appraisal (see below). The further surveys required to inform an EcIA (sometimes referred to as Phase 2 surveys) will vary depending on the location, nature and scale of the proposed development, the habitats present on site, and the resulting likely or potential impacts. They may include, for example, surveys to confirm the presence or likely absence of a protected species, or detailed botanical surveys of a potentially important habitat. In many cases it is not possible to predict exactly which further surveys will be required prior to completing the Preliminary Ecological Appraisal.

In Northern Ireland, the NI Biodiversity Checklist has been produced. This is intended to be a step by step tool to help applicants determine whether a proposal is likely to affect biodiversity interests and whether further ecological assessments or surveys may be required. This can be found at:

Planning applications for projects affecting a homeowner’s residence may only require assessment in relation to specific species, such as roosting bats. CIEEM has produced advice for UK homeowners on commissioning bat surveys.

For projects requiring an Environmental Impact Assessment (EIA)3, the EcIA process should be used to provide the ecological component of that assessment.

For projects requiring planning consent or other form of consent, but where an EIA is not required, the EcIA process should be followed and the outcomes presented in an EcIA Report. EcIA Reports should follow the guidance on structure and content set out in CIEEM’s Guidelines for Ecological Report Writing, and should allow the decision maker to answer the following key questions:

  • Does the project accord with relevant planning policy and legislation?
  • Is any mitigation and/or compensation required? If so, what is proposed and how can it be secured?
  • What are the overall outcomes for biodiversity if the project goes ahead?

EcIA Reports should also be produced for permitted/exempted and other development generally granted consent by a Development Order, although planning policy may not apply in all cases.

Preliminary Ecological Appraisal (PEA) is the term used to describe a rapid assessment of the ecological features present, or potentially present, within a site or the surrounding area (within the Zone of Influence for a proposed project). It normally comprises a desk study and a walkover survey, such as an Extended Phase 1 Habitat Survey. See CIEEM’s Guidelines for Preliminary Ecological Appraisal.

A PEA can be undertaken in a variety of contexts, often as a preliminary assessment of likely impacts of a development project. It can help the project proposer and planning authority in scoping4 the subsequent EcIA or in concluding that ecological issues will not be significant in determining the application.

The results of the PEA can be provided in a PEA Report (PEAR) (guidance on structure and content is set out in CIEEM’s Guidelines for Ecological Report Writing) or simply incorporated into the EcIA Report, ecology component of an EIA, or a Scoping Report5, as needed.

A PEAR does not replace an EcIA Report, as it normally contains recommendations for further surveys or general design advice to a developer, rather than a detailed assessment of the effects of a finalised scheme, with all required ecological surveys completed. For very straightforward projects, where no further ecological surveys are needed an EcIA Report can be produced following completion of the PEA.

A Habitats Regulations Assessment (HRA) (in Scotland called a Habitats Regulations Appraisal and in Ireland called an Appropriate Assessment) is required, under the provisions of the EU Birds and Habitats Directives, where any proposal (including permitted development) may have a significant effect on a ‘European Site’6. In this context ‘significant’ means any effect on the features for which the site has been designated, which could undermine the site’s conservation objectives, and which cannot be excluded on the basis of objective information. Where such an effect may occur, applying the precautionary principle and if necessary considering the combined effects of other plans or projects that may affect the same site, an ‘appropriate assessment7 will be required in accordance with the relevant statutory Regulations. The Conservation of Habitats and Species Regulations 2010 are the most commonly used in England and Wales. If there is any doubt about the likelihood or significance of the effects of a proposal on a European or Ramsar site the statutory nature conservation body should be consulted because the legislation is precautionary and subject to established European and UK case law8. In Ireland, the information provided for Appropriate Assessment is within a document called a Natura Impact Statement9.

The British Standard on biodiversity (BS42020:2013 Biodiversity – Code of Conduct for Planning and Development) seeks to promote transparency and consistency in the quality and appropriateness of ecological information submitted with planning applications and in the way that decisions and actions are made in light of that information. It brings together useful recommendations and encourages good practice in taking account of biodiversity through the planning process. The Standard provides guidance on a range of relevant issues, such as pre-application surveys, securing appropriate planning conditions, implementing mitigation measures during construction, and undertaking management and monitoring after the construction phase is completed.

Proponents of development projects may make a commitment to deliver no net loss or net gain to biodiversity on a corporate or project-specific basis or be required to achieve no net loss or net gain by a planning authority as a result of local planning policies. A development project aiming for no net loss must achieve a balance of at least equivalent gains for biodiversity in comparison with losses, with respect to species, habitats, ecosystem functions and services associated with biodiversity. Net gain aims to provide additional conservation outcomes that go beyond substitution for losses. CIEEM has published core Principles on Net Gain in partnership with IEMA and CIRIA.

A biodiversity offset is a way to demonstrate that a plan or project can be implemented in a manner that results in no net loss or a net gain of biodiversity. Outcomes should be measurable and should compensate for residual adverse impacts to biodiversity arising from development, after appropriate prevention and mitigation measures have been taken10.

CIEEM provides training (see full listings) on topics relating to ecological assessment for development projects including:

  • Ecological Impact Assessment – Beginner, Intermediate and Advanced levels
  • Ecological Report Writing
  • Report Writing for EcIA
  • Habitat Regulations Assessment
  • British Standard BS42020 Biodiversity – Code of Practice for Planning and Development
  • Preliminary Ecological Appraisal
  • Using biodiversity metrics



  1.  JNCC (2010) Handbook for Phase 1 habitat survey – a technique for environmental audit. Joint Nature Conservation Committee, Peterborough
  2. Fossitt (2000) A Guide to Habitats in Ireland. The Heritage Council, Kilkenny.
  3. Environmental Impact Assessment (EIA) is the process used to assess the effects of certain public and private projects on the environment in order to meet the requirements of Council Directive 85/337/EEC as amended by Council Directives 97/11/EC, 2003/35/EC and 2009/31/EC and redrafted in a codified version Directive 2011/92/EU. The amended Environmental Impact Assessment (EIA) Directive 2014/52/EU entered into force in 2014 to simplify the rules for assessing the potential effects of projects on the environment and Member States have to apply these rules from May 2017.
  4. Scoping is the process of determining the content and extent of an EcIA.
  5. Scoping Reports are often produced as a means of consulting on the scope of an EIA.
  6. A ‘European Site’, in this context, is any Special Protection Area classified under the EU Birds Directive or a Special Area of Conservation designated under the EU Habitats Directive, or sites which are being considered for such a status, or which are currently going through the stages of the classification/designation process. As a matter of Government policy ‘European Sites’ also include listed Ramsar Sites.
  7. Appropriate assessment is the term used for an assessment, required by the EU Birds and Habitats Directives, for any proposal that may have a significant effect on the features for which a European or Ramsar Site has been designated. ‘Appropriate’ in this context means suitable for the purpose of meeting the objectives of the Directives, but the assessment is based on the precautionary principle and there is extensive UK and EU case law prescribing what such an assessment should comprise. If permission is to be granted, the assessment should be sufficient to enable the planning authority to ascertain that there would not be an adverse effect on the integrity of the site.
  8. Further information can be found in the Habitats Regulations Assessment Handbook.
  9. Further information can be found in Appropriate Assessment of Plans and Projects in Ireland: Guidance for Planning Authorities.
  10. A national pilot programme for biodiversity offsetting in England was undertaken by DEFRA between 2012 and 2014. The final evaluation report, published in 2016, can be accessed at