Ecological survey calendar: when can wildlife surveys be carried out?

 

If a planning application may affect protected species, the timing of the ecology work can be just as important as the planning drawings. Some surveys can be carried out throughout the year. Others depend on a relatively short seasonal window, suitable weather or a particular stage in the species’ life cycle.

Miss the right window and the consequence may not be a small delay to an ecology report. If the local planning authority needs that survey information to properly understand and determine the application, you may have to wait until the next suitable season before the application can be decided.

This page gives a practical survey timetable for planning applications in England, based principally on current Natural England standing advice. It is a guide to planning the programme, not a substitute for a qualified ecologist deciding which surveys are actually necessary for your site. The separate legal, mitigation and licensing issues are explained in our guide to protected species and planning.

 

The quick rule: ecology can control your planning timetable

 

Natural England’s standing advice tells local planning authorities to make sure surveys are undertaken at the correct time of year using appropriate methods, and says they should not normally decide a planning application until the necessary protected-species surveys have been received.

It also says councils should not usually attach a condition requiring the basic survey work to be done later. The reason is straightforward: the authority generally needs enough ecological information to understand the likely impact before it grants permission. Conditions can still be appropriate for additional or updated work in particular circumstances, for example on outline or phased schemes, but they are not the normal answer to a missing survey.

That makes early ecology work particularly important where you are working to a purchase deadline, option agreement, funding date or construction programme. If a bat survey window closes before the planning team realises it is required, the planning programme can move by months.

 

Do you need every survey in this calendar?

 

No. The calendar shows when particular surveys can usually be undertaken; it does not mean every development needs them.

The sensible first step is normally a proportionate ecological review of the site. A Preliminary Ecological Appraisal (PEA) commonly combines a desk study and walkover survey to identify likely ecological constraints and decide whether more detailed habitat or species surveys are needed. CIEEM describes the PEA as an early-stage tool for identifying constraints, mitigation and further survey requirements; it should not automatically be treated as the final ecology evidence for a planning application.

Natural England’s standing advice gives examples of habitats which should prompt consideration of protected species. Traditional buildings can indicate bats and nesting birds; ponds and ditches can raise great crested newt and water-vole issues; rough grassland and brownfield land can support reptiles and invertebrates; woodland, scrub and hedgerows can support bats, birds, dormice and badgers.

If the development is near an SSSI, SPA, SAC or Ramsar site, there may also be protected-site issues that are separate from individual species surveys. See our guide to Habitats Regulations Assessment.

 

Protected-species survey timetable

 

The table below uses Natural England’s current national timetable as a planning guide. The dates are indicative, not statutory deadlines. Weather, geography, survey purpose, species behaviour and professional guidance can all affect whether a survey is valid.

Important: Natural England expressly says its timetable is dependent on weather conditions and is only an indication of survey timing and requirements. The relevant species guidance and professional survey standards still need to be followed.

 

At-a-glance month-by-month calendar

 

This simplified grid shows the main nationally indicated survey windows. A dot means that the month falls within the broad Natural England window; it does not guarantee that weather or site conditions are suitable on a particular day.

 

● month broadly within the stated window. ◐ only part of that month is within the stated window.

 

Why a Preliminary Ecological Appraisal should come early

 

The calendar is most useful when it is used before the design and planning programme are fixed.

A competent ecologist can use an early site appraisal to identify likely constraints and decide what follow-up work is proportionate. That can influence the layout before the proposal has become expensive to redesign. It can also expose seasonal risks while there is still time to act on them.

For example, an old roof, barn, mature tree or wooded edge may trigger bat work. A pond within the surrounding landscape may raise great crested newt questions. A ditch, stream or river may need water-vole or otter consideration. Rough grassland, scrub or brownfield habitat may require reptile or invertebrate work. The exact requirement depends on the impact pathway, not simply whether the species has ever been recorded nearby.

 

What if you miss the survey season?

 

Sometimes the answer is unfortunately: you wait.

If the authority cannot understand the likely ecological effect without a seasonally constrained survey, submitting the application without it may lead to an invalid application, a request for further information, an extension of time or refusal. Whether the application is technically valid depends on the national requirements and the council’s current local validation requirements, but validity and planning acceptability are different questions. An application can be valid and still lack enough ecological evidence to be approved.

There are situations where a qualified ecologist may advise that additional survey is unnecessary, or where a recognised alternative approach can be used. Natural England’s licensing policy can sometimes allow a robust worst-case approach instead of additional European-protected-species survey effort. That is a professional and case-specific judgment, not a general shortcut for a missed season.

 

Great crested newts and District Level Licensing

 

Great crested newts are a good example of why a simple calendar is not the whole story.

Traditional survey work is highly seasonal, but Natural England’s District Level Licensing (DLL) provides an alternative approach in areas where a scheme is available. Where the developer chooses the DLL route, the conventional planning-survey and mitigation process can be different. Natural England describes DLL as a simpler route under which developers contribute towards strategically located compensation ponds.

So do not automatically commission a traditional great crested newt survey simply because there is a pond nearby. First establish whether DLL is available, whether it is appropriate for the proposal and what information the chosen route requires.

 

Survey timing is not the same as the timing of works

 

This distinction catches people out.

The fact that a species can be surveyed in a particular month does not mean destructive or disturbing works can lawfully take place in that month. Survey seasons, ecological mitigation periods, nesting seasons and wildlife-licence conditions are separate issues.

For example, a bat preliminary roost assessment may be undertaken year-round, but that does not give permission to disturb a roost. A breeding-bird survey window does not replace the separate legal protection applying to active nests. A badger survey may be possible year-round while particular licensable works are subject to different restrictions.

The project programme therefore needs to consider three different dates: when evidence can be collected, when planning can be determined, and when the works can lawfully be carried out.

 

How old can an ecology survey be?

 

There is no universal rule that every ecological survey expires after a fixed number of months. CIEEM’s advice on the lifespan of ecological reports says validity is context-dependent: habitats change, species move, the development proposal can change and particular licensing regimes can have their own requirements.

Natural England gives some species-specific guidance. For example, its great crested newt standing advice says survey information should be no older than four survey seasons and still reflect the current site. Where an application or reserved-matters programme runs for a long time, updated evidence may therefore be required.

An old ecology report should not simply be copied into a fresh application because it once supported a permission on the same site.

 

Ecology, BNG, HRA and EIA are not the same exercise

 

A protected-species survey deals with particular species and their habitats. It should not be confused with:

• Biodiversity Net Gain, which measures the statutory biodiversity value of habitats for applicable development
• Habitats Regulations Assessment, which deals with effects on protected habitats sites
• Environmental Impact Assessment, which is a wider statutory environmental assessment regime for qualifying projects
• tree and woodland controls, including ancient woodland and veteran trees

A single project can require several of these at once. Good early ecological work should identify how they fit together rather than producing separate reports which discover each other’s problems too late.

 

Practical programme for an applicant

 

1. Check the site early. Do not wait until the planning drawings are complete before asking whether ecology matters
2. Commission an appropriate preliminary appraisal. The ecologist should identify likely protected-species and habitat issues and any further survey requirement
3. Map the survey windows against the planning programme. Identify the last realistic survey date rather than just the planning submission date
4. Let ecology influence the design. Avoidance is usually better than designing a scheme first and trying to mitigate the damage afterwards
5. Check the local validation list. Councils can have locally specific biodiversity evidence requirements. See our guide to local validation lists in England
6. Submit enough information for a decision. Do not assume a condition will rescue a missing seasonal survey
7. Recheck before works start. Planning permission does not override wildlife legislation or any separate licence requirement

 

Key sources

 

• Natural England and DEFRA: Protected species and development – advice for local planning authorities
• Natural England: Bats – advice for making planning decisions
• Natural England: Great crested newts – advice for making planning decisions
• CIEEM: Guidelines for Preliminary Ecological Appraisal
• CIEEM: Advice note on the lifespan of ecological reports and surveys

 

Other Planning Application Sections

 

Ecological Survey Calendar Page Added: 21st August 2026