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Do you need a Bat Roost Surveys?

bat roost surveys

The bat roost survey season is upon us. The agb Environmental team of ecologists are ready with their various bat detectors to turn slightly nocturnal themselves!

Bat roost assessments may be required for buildings and trees. Your Preliminary Ecological Appraisal (or Preliminary Roost Assessment, often forming part of the PEA) will identify whether a bat roost assessment is required. (Both of which can be completed throughout the year).

Finding an ecologist to undertake a bat survey can be complex, as the ecologist must have a licence to survey or bats, particularly where a roost is known to exist.

Buildings may require between one and three emergence (dusk) / re-entry (dawn) surveys, depending on the level of roosting suitability. Emergence / re-entry surveys are only possible between May and August, though shoulder months may be feasible, but are sub-optimal. All surveys must be spaced at least two weeks apart. The majority of surveys should be between May and August for buildings with high roosting potential.

In some cases, an appropriately licenced and trained ecologist can climb trees to investigate for bats, thereby reducing the need for emergence / re-entry surveys on the trees (agb Environmental has a licenced bat ecologist with a tree climbing certificate).

Bat roosts are legally protected therefore a Mitigation Licence before works are undertaken that may impact the roost. In most cases, the mitigation is straight forward, provided that the survey effort was sufficient. However, the type and level of mitigation depends on the bat species, type of roost, numbers of bats, and the impacts of a proposal.

Get in touch

agb Environmental teams have experience of undertaking the full range of bat surveys. We have several bat licenced ecologists throughout the south of England. For more information on bat roost surveys, please contact Richard Parmee (Head of Natural Environment) on 01638 663226 or email

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