Guide
Preliminary bat roost assessment: what it is, the cost, what comes next
Updated
A preliminary bat roost assessment (PRA) is a daytime inspection of a building, inside and out, for signs of bats and features they could use, and it can be done in any month. Six UK consultancies publish a starting price between £200 and £399, a median of £349, and its result decides whether you need no more surveys or one to three dusk emergence surveys in summer.
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What the ecologist does
The Bat Conservation Trust's Bat Surveys for Professional Ecologists: Good Practice Guidelines (4th edition, 2023) defines a PRA as a detailed inspection of the exterior and interior of a structure to look for features bats could use to get in, out and roost, and to search for signs of bats (para 5.2.1). In practice that means the roof void, the eaves, soffits, ridge tiles and gaps in brickwork, and the droppings, staining and feeding remains that show bats have been there. The guidelines say plainly that not finding evidence is not proof bats are absent, which is why the PRA grades the building's suitability rather than declaring it clear.
It can be done in any month
PRAs can be carried out at any time of year, providing any limitations are recognised and reported (para 5.2.35). That makes it the one bat survey you can commission the week you start designing, and it is the reason to do it first: emergence surveys are tied to the summer season (see bat survey season), and finding out in October that you need them usually means waiting until May.
What the result leads to
| PRA result | Further surveys | When |
|---|---|---|
| Negligible suitability | Usually none: the report closes the question for planning | Not needed |
| Low suitability | One dusk emergence survey (more where several low-rated buildings are involved) | May to August |
| Moderate suitability | Two separate dusk emergence surveys | May to September, at least one between May and August |
| High suitability | Three separate dusk emergence surveys | May to September, at least two between May and August |
Where more than one visit is needed, the guidelines recommend spacing them at least three weeks apart. At typical emergence survey prices (see bat emergence survey cost), the PRA's grading is the single biggest number in your survey budget.
Preliminary roost assessment cost
| Consultancy | Published price |
|---|---|
| Indigo Surveys | from £200 + VAT |
| BatSurveys.co.uk | from £299 + VAT |
| Chase Ecology | from £348 (with a habitat walkover) |
| Aware Ecology | from £350 + VAT |
| Gritstone Ecology | £350 |
| Arbtech | from £399 + VAT |
The six published starting prices run from £200 to £399 with a median of £349. Most firms publish a starting figure only, because travel, the size of the building and the number of structures move the price; Indigo Surveys notes a PRA is usually around a day's work. Most consultancies publish no PRA price at all, which is why comparing quotes for your own building is worth the two minutes the form takes.
Survey effort figures are the Bat Conservation Trust's recommended minimums for structures; your ecologist may justify more or fewer visits for your site. Prices are starting figures as published and change; nothing here is legal advice.