Guide
How long is a bat survey valid for? 12 months, 18 months, 3 years
Updated
A bat survey is likely to be valid for 12 months in most cases, and usually for up to 18 months, according to the Chartered Institute of Ecology and Environmental Management (CIEEM); between 18 months and 3 years an ecologist must revisit and say whether it still stands, and after 3 years the report is unlikely to be valid at all. Bats are mobile, so a survey of a building is one of the first CIEEM expects to need updating.
Get bat survey quotes Two minutes of questions; licensed ecologists covering your area quote you directly. Free, no obligation.
The age bands planners work to
| Age of the survey | What CIEEM advises |
|---|---|
| Less than 12 months | Likely to be valid in most cases. |
| 12 to 18 months | Likely to be valid in most cases, except where a mobile species could use existing or new features, where a mobile species can create new features, or where country or species guidance says otherwise. |
| 18 months to 3 years | A professional ecologist must visit the site, update the desk study, and issue a clear statement on whether the report is still valid and which surveys need updating. |
| More than 3 years | Unlikely to still be valid; most, if not all, surveys are likely to need updating. |
The table is CIEEM's general advice (CIEEM Advice Note, April 2019). Natural England's standing advice for planning authorities points to the same note when it tells councils to check the valid age of ecological reports (Bats: advice for making planning decisions).
Why bat surveys date faster than most
CIEEM's own first example is a bat case: trees or buildings surveyed with no roost found may since have gained new roosts or new features, so an update bat roost survey is likely to be required. The note also says the chance of needing an update rises with time and is greater for mobile species. Natural England adds that bat surveys must be carried out in the most recent appropriate season, so a survey that is past its season and the project's timetable can cost you a full summer (standing advice; see bat survey season).
A licence application may need newer data
CIEEM's note says its bands apply where no more specific guidance exists, and names the age of data used to support a European protected species licence as one place where it does. If your project needs a Natural England bat mitigation licence, ask your ecologist what age of survey the licence application will accept before relying on an older report.
What an update costs
An update within the 18 month to 3 year band starts with a site visit and a review, which is the same daytime inspection as a preliminary roost assessment. Thirteen UK consultancies publish a starting price for bat survey work between £200 and £500, with a median of £350 (UK Bat Survey Price Index). If the review finds the building has changed or bats may have moved in, emergence surveys follow and are priced per visit (see bat emergence survey cost).
What to ask a firm
- My survey is dated [month and year]: which CIEEM band does it fall in for my planning submission?
- Will a review visit be enough, or do you expect emergence surveys again this season?
- Will the update also satisfy a Natural England licence application if I need one?
- Can you state in the report how long you expect it to remain valid?
CIEEM's bands are professional guidance, not law; the planning authority decides whether survey evidence is adequate for its decision. Prices are published starting figures and change.