If you're applying for planning permission in the UK, there's a good chance your local planning authority will ask for an ecological survey. In most cases, the first thing you need is a Preliminary Ecological Appraisal - or PEA.
This guide explains what a PEA is, what it involves, when you need one, how much it costs, and what happens after.
What Is a PEA?
A Preliminary Ecological Appraisal is the standard first-stage ecological assessment for a development site. It's also known as an Extended Phase 1 Habitat Survey, a Phase 1 Ecology Survey, or simply an ecological scoping survey.
A PEA has two components:
- A desk study - gathering existing data about the site and its surroundings from online databases, record centres, and planning records
- A walkover survey - a site visit by a qualified ecologist to map habitats, assess the potential for protected species, and identify ecological constraints
The purpose of a PEA is to establish the ecological baseline of a site. It tells you what habitats are present, whether protected species are likely to be there, and whether any further detailed surveys are needed before a planning application can be determined.
When Do You Need a PEA?
You are likely to need a PEA if your development proposal involves any of the following:
- Demolition or conversion of buildings (particularly older buildings, barns, and agricultural buildings where bats may roost)
- Clearance of more than 25 square metres of vegetation or natural habitat
- Removal of more than 5 metres of hedgerow
- Works within 500 metres of a pond or waterbody (potential GCN habitat)
- Works within or adjacent to a watercourse (potential otter and water vole habitat)
- Works within the Zone of Influence of a designated site (SSSI, SAC, SPA, Local Wildlife Site, Ancient Woodland)
- Works to roofs, lofts, or roof spaces (potential bat roost features)
- Any development on greenfield land
Many local planning authorities publish ecological checklists or validation requirements that specify when an ecological survey is needed. If in doubt, check with your LPA's ecology officer before submitting your application.
Important: Your LPA will not accept a planning application without the required ecological information. Submitting without it will result in an invalid application or a request for additional information, causing delays.
What Does the Desk Study Involve?
The desk study is the information-gathering phase. Your ecologist will search for existing ecological data about the site and its surroundings, typically within a 1-2km radius (larger for European designated sites).
The desk study covers:
- Statutory designated sites: SSSIs, SACs, SPAs, Ramsar sites, NNRs, AONBs/National Landscapes, LNRs within the search buffer
- Non-statutory designated sites: SINCs, Local Wildlife Sites, County Wildlife Sites
- Protected species records: Existing records of bats, GCN, dormouse, otter, water vole, badger, reptiles, barn owl, and other protected species
- Priority habitats: Ancient Woodland, Priority Habitat Inventory
- GCN risk zones: District Level Licensing risk zone classification
- Planning constraints: SSSI Impact Risk Zones, local plan ecology policies
Data sources include MAGIC Map, NBN Atlas, NatureScot (Scotland), NRW/DataMapWales (Wales), and Local Environmental Records Centres (LERCs). A LERC data search is recommended best practice as they hold detailed local records that may not appear on national databases.
Pro tip: Use EcoCheck to run the designation and species records component of your desk study instantly. It queries all the main national data sources for any GB location in seconds, giving you a comprehensive screening before you even visit the site.
What Does the Walkover Survey Involve?
The walkover is a site visit by a qualified ecologist, typically lasting 2-4 hours depending on site size. The ecologist will:
- Map all habitats present on site using the UK Habitat Classification System (UKHab)
- Record plant species to help classify habitat types
- Assess bat roost potential of any buildings or trees on or near the site
- Look for evidence of protected species - badger setts, otter spraints, water vole latrines, reptile refugia, nesting birds
- Assess habitat suitability for species that may not leave obvious signs - dormouse habitat, GCN terrestrial habitat, invertebrate habitat
- Identify invasive non-native species - Japanese knotweed, Himalayan balsam, giant hogweed
- Note ecological constraints that could affect the development design
The walkover can be done at any time of year, but April to September is optimal because vegetation is identifiable and animals are more active.
What Does a PEA Report Include?
The PEA report is a formal document that gets submitted with your planning application. It typically includes:
- Survey methodology and any limitations
- Desk study results (designated sites, species records, habitat data)
- Habitat map of the site
- Assessment of ecological features and their importance
- Assessment of potential impacts from the proposed development
- Recommendations for further surveys (Phase 2 surveys) if needed
- Recommendations for mitigation, compensation, and enhancement
- Relevant legislation and planning policy
- Qualifications of the surveyor
The report should follow CIEEM (Chartered Institute of Ecology and Environmental Management) guidelines for Preliminary Ecological Appraisal.
What Happens After a PEA?
If the PEA identifies potential for protected species, further Phase 2 surveys will be recommended. These are species-specific surveys carried out during the appropriate season:
- Bats: Emergence/re-entry surveys (May-August)
- Great crested newts: Pond surveys or eDNA (mid-March to June)
- Reptiles: Refugia surveys (April-May, September)
- Dormouse: Nest tube surveys (April-November)
- Water vole: Bankside surveys (mid-April to September)
- Badger: Sett surveys (year-round, best Feb-April)
- Breeding birds: Dawn surveys (April-June)
If no further surveys are needed - because the PEA found no evidence of ecological constraints - the PEA report itself is sufficient to support the planning application.
The PEA will also need to consider Biodiversity Net Gain (BNG) requirements, which are mandatory for most planning applications in England since February 2024. Your ecologist should advise on how BNG applies to your specific development.
How Much Does a PEA Cost?
PEA costs vary depending on the size and complexity of the site, geographic location, and the consultancy you use. As a rough guide:
- Small residential site (single house, garden, small plot): £400-800
- Medium site (housing development, commercial building): £600-1,500
- Large or complex site (industrial estate, mixed-use development): £1,500-3,000+
These costs include the desk study, site visit, and report. LERC data search fees (typically £100-375) are usually charged separately.
Phase 2 species surveys, if required, are additional and can add significantly to the total ecological survey cost depending on which species are involved and how many survey visits are needed.
How Long Is a PEA Valid For?
A PEA report is generally considered valid for 18 months to 2 years from the date of the site visit. After that, the ecological conditions on site may have changed and an update or new survey may be required.
If there is a significant time lag between the PEA and the start of development, your LPA may require an updated survey. It is good practice to re-check the site before works begin, even if the PEA is still within its validity period.
Choosing an Ecologist
Your PEA must be carried out by a qualified and experienced ecologist. Look for:
- CIEEM membership: Members of the Chartered Institute of Ecology and Environmental Management follow a code of professional conduct and meet competency standards
- Relevant experience: An ecologist who has worked on similar sites and habitats in your area
- Species licences: If Phase 2 surveys are likely, check that the ecologist or their team hold the relevant species survey licences (bat licence, GCN licence, etc.)
- Professional indemnity insurance: Standard for any ecology consultancy
You can search the CIEEM directory at cieem.net to find registered practices and individual members.
Start With the Data
Before your ecologist visits site, the desk study sets the context. Knowing what's designated nearby, what species have been recorded, and what the GCN risk zone is helps the ecologist focus the walkover on the features that matter.
EcoCheck gives you that context instantly. Run a search on your site location and you'll know before the site visit whether there are SSSIs within 2km, whether bats have been recorded nearby, and whether you're in a GCN red, amber, or green zone.
Patrick O'Connor is a Freelance Ecologist at Kinterra Consulting and the developer of EcoCheck - an instant ecological desktop assessment tool for any GB location. Try it free for 3 days at ecocheck.co.