Survey brief for a bat emergence programme on a barn
A two page brief that tells the ecologist how many emergence visits you are buying, what weather aborts a visit and what the report must contain, before you compare quotes.
A bat survey brief for a barn is a procurement document, not a wish list. Write it badly and you get a preliminary roost assessment in November, a recommendation for three emergence visits the following summer, and a scheme that slips a full season. Write it properly and the ecologist knows how many visits are being priced, what weather will abort a visit, what the report must contain for the council to validate the application, and who carries the licensing work if a roost is confirmed. Everything below assumes a traditional agricultural building in England, the kind that comes up in Class Q conversions and barn reuse schemes.
Bat survey work must be carried out by a suitably licensed ecologist. All bat species are protected under the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017, and a survey licence is needed to disturb a roost or handle a bat. This is one area where no draft document and no desk study substitutes for the licensed person.
What the preliminary assessment must establish
The first visit is a preliminary roost assessment, and it can be done at any time of year. Ask for it to deliver five specific outputs rather than a general appraisal.
- A suitability category for the building, recorded as negligible, low, moderate or high potential, with the features that drove the category named and photographed.
- An internal and external inspection of every accessible elevation and the roof void, with a note of anything that could not be reached and why.
- A record of field signs: droppings, feeding remains, staining at gaps, urine splashes on beams.
- A description of the surrounding habitat and connectivity, because a barn in the middle of arable land and a barn on a hedgerow network are not the same proposition.
- A clear statement of the further survey effort the category implies, with dates.
That last output is the one that protects your programme. A suitability category on its own tells you nothing about cost.
Number and timing of emergence visits
Survey effort follows the suitability category, using the survey effort framework in the Bat Conservation Trust good practice guidelines. Low suitability buildings normally need a single emergence or re-entry visit. Moderate suitability normally needs two. High suitability normally needs three, spread across the season rather than clustered into a fortnight.
| Suitability | Typical emergence or re-entry visits | Spacing |
|---|---|---|
| Negligible | None | Not applicable |
| Low | 1 | Within the optimal window |
| Moderate | 2 | At least two weeks apart |
| High | 3 | Spread across the season |
The season is the constraint that ruins programmes. Emergence surveys run from May to September, and the optimal window for establishing roost status is May to August. A preliminary assessment in October that finds moderate potential means the application evidence cannot be completed until the following May at the earliest. Put that sentence in the brief so nobody is surprised by it later.
Ask for proposed survey dates at the point of appointment, not after the first visit. And ask what happens if a visit is aborted, because the answer determines whether the replacement visit lands inside the window or outside it.
Surveyor numbers and equipment
Emergence surveys count bats leaving a building, so every elevation with a potential access point needs a pair of eyes on it. For a modest single storey barn with two open elevations, two surveyors may be enough. For an L shaped range with a cart entrance, a lean to and several gable apex gaps, four is more realistic. Specify the coverage requirement rather than a headcount: every elevation with identified potential access features must be observed for the full survey period.
The brief should also state:
- Survey period, from 15 minutes before sunset to at least 90 minutes after for emergence work, and from 90 minutes before sunrise to sunrise for re-entry work.
- Full spectrum or time expansion detectors with recordings retained for later analysis, not heterodyne only.
- Infrared or thermal video where an access point cannot be watched directly.
- Whether static detectors are to be deployed, for how long, and who analyses the data.
Recordings and their analysis matter for review. An ecologist who keeps the sound files can defend a species identification. One who does not cannot.
Weather criteria and aborted visits
Bats do not emerge reliably in cold, wet or windy conditions, and a survey run in poor weather is not evidence of absence. Set the criteria in the brief so that the decision to abort is not a negotiation on the night.
Reasonable criteria are a temperature at sunset of at least 10 degrees Celsius, no persistent or heavy rain, and wind below a level that makes detector recordings unusable. Ask for the actual temperature, wind and rainfall to be recorded for every visit and reported in a table. Where a visit is completed in marginal conditions, the report should say so rather than presenting the result as equivalent to a good night.
Price the abort risk explicitly. A brief that says aborted visits are rescheduled at no additional fee will cost more up front and less overall.
Reporting content the council expects
A council validating an application wants to see the survey effort, the results and the consequences, in that order. Specify the report contents in the brief:
- Methods, including dates, times, weather, surveyor positions and equipment, with a figure showing where each surveyor stood.
- Results by visit, with species, counts, times and emergence points marked on an elevation drawing.
- An assessment of roost status and, where a roost is present, its type: day roost, night roost, feeding perch, maternity or hibernation.
- Impact assessment against the proposed works, referencing the drawings by number and revision.
- Mitigation and compensation proposals, with location, specification and timing, and the monitoring that follows.
- A statement on whether a licence will be required.
Ask for the mitigation to be drawn, not just described. A bat loft shown on a section drawing gets conditioned cleanly. A bat loft described in a paragraph invites a condition requiring further details before work starts, and another round of information.
Where the application also needs a wider ecological baseline, the bat work usually sits inside a Preliminary Ecological Appraisal rather than standing alone, and the two should share one set of habitat plans.
Licensing implications if a roost is confirmed
Finding a roost does not stop a conversion. It changes the consent route and the programme. Where works would damage or destroy a roost, or disturb bats, a European protected species mitigation licence from Natural England is needed before those works start, and planning permission must normally be in place first because the licence application relies on the approved scheme.
The three tests the licensing authority applies are that the works serve an overriding public interest or other permitted purpose, that there is no satisfactory alternative, and that the favourable conservation status of the species is maintained. Your ecologist writes that case. Build the time for it into the programme, and be aware that the council's own decision must engage with the same tests, because an authority that grants permission without considering them is exposed on appeal.
Ask in the brief whether the ecologist holds the relevant class licences or registrations, and whether licence application drafting and post consent monitoring are inside the fee or outside it. That single question removes most of the arguments that arise later.
Wording the brief before you appoint
Keep it to two pages. State the site, the building, the proposed works and the drawing numbers. State the outputs you are buying: preliminary roost assessment, a stated number of emergence or re-entry visits determined by the category, a report to the content list above, and a priced option for licence support. State the deadline you are working to and ask the ecologist to tell you plainly whether the season allows it.
Then ask for three things that are easy to forget. Professional indemnity cover and its level. Membership grade of the relevant professional body. Confirmation that survey recordings and raw data will be supplied with the report.
Send the same brief to everyone you approach. Quotes that cover different survey effort are not comparable, and the lowest quote is usually the one that has assumed low suitability before anyone has looked at the building.
This is general guidance, not legal advice; check the position with your local planning authority or a qualified professional before relying on it.
A PlanScope draft can structure the supporting statements around the ecology evidence, including the Protected Species Survey scope and the design and access statement for a barn conversion, while the survey itself stays with your licensed ecologist. For specialist technical reports, qualified professional input may be required.
PlanScope provides AI-assisted draft reports for planning applications. Reports should be reviewed before submission. We do not guarantee planning approval.
Frequently asked questions
How many bat emergence surveys does a barn need?
It depends on the suitability category from the preliminary roost assessment. Low suitability buildings normally need one emergence or re-entry visit, moderate suitability two, and high suitability three spread across the season. The category is set by roosting features, field signs and surrounding habitat, so the number cannot be fixed before an ecologist has inspected the building.
When can bat emergence surveys be carried out?
Emergence and re-entry surveys run from May to September, with May to August the optimal window for establishing roost status. The preliminary roost assessment can be done at any time of year. A preliminary assessment in autumn that finds moderate or high potential means the survey evidence cannot be completed until the following spring at the earliest.
Do I need a licensed ecologist for a bat survey?
Yes. Bats and their roosts are protected under the Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017, so survey work that involves disturbing a roost or handling a bat requires a suitably licensed ecologist. No desk study or draft document substitutes for the licensed person, and councils will not accept survey evidence from an unlicensed author.
What weather conditions abort a bat survey?
Cold, persistently wet or windy nights produce unreliable results. A workable specification is a temperature at sunset of at least 10 degrees Celsius, no persistent or heavy rain, and wind low enough for usable detector recordings. Ask for the actual conditions to be recorded for every visit, and agree in advance who bears the cost of rescheduling an aborted visit.
What happens if a bat roost is found in the barn?
The conversion can still proceed, but the route changes. Works affecting a roost need a European protected species mitigation licence from Natural England, normally applied for after planning permission is granted, supported by a mitigation scheme your ecologist prepares. Build the licence period into the programme and ask upfront whether licence drafting and monitoring are inside the quoted fee.
Sources and further reading
This article is general guidance about the planning system in England and, where stated, the rest of the UK. It is not legal or professional advice. Check your local planning authority’s validation requirements and take professional advice for your specific site.