When are Bat Activity Surveys Required?
Bat activity surveys may be required, particularly for larger sites or where there may be an impact upon habitat features likely to be of use to foraging or commuting bats. These impacts could occur as a result of the removal of trees, woodland or hedges or through the severing of habitat features such as hedgerows or lines of trees. Bat Activity Surveys may be requested for single wind turbines, wind farms and new lighting as they may also impact upon foraging and commuting bats.
Bat Activity Survey at Windfarm in NI 
Static bat detector deployed during bat activity surveys
What is a Bat Activity Survey?
Bat activity surveys follow standard methods as described by the Northern Ireland Environment Agency (NIEA) (available here) and the Bat Conservation Trust (BCT) and include conducting a number of walked transects with a bat detector and the deployment of static bat detectors.
Walked transects are conducted during the bat active season (Apr-Sep inclusive) and cover the area within the site boundary plus up to 100m beyond, where safe and accessible. Transects include a number of timed listening points to provide a representative sample of bat activity within the area.
NIEA and BCT also have the following requirements for emergence/re-entry surveys:
- All surveys must take place during the bat active season (Apr-Sep inclusive)
- All surveys must be conducted during suitable weather conditions (not wet, windy or cold)
How much does a Bat Activity Survey cost?
The cost ultimately depends upon the number of survey visits required and the number of static bat detector locations required.
The number of survey visits stipulated in the BCT Guidelines relate to the overall quality of the bat foraging and commuting habitat on the site and in surrounding areas. Bat habitat quality is classified as low, moderate or high according to BCT Guidelines. The requirements for the minimum number of survey visits for each habitat quality class have been recently reviewed and updated (Collins, J. Ed, 2016) and are summarised below:
Low Bat Habitat Quality:
One survey visit per season (Spring, Summer, Autumn) plus one static detector location per transect. Static bat detector d
Cost: From £1,700*
Moderate Bat Habitat Quality:
One survey visit per month (April – September) plus two static detector locations per transect. Static bat detector data to be collected on 5 consecutive nights per month (April – September).
Cost: From £3,000*
High Bat Habitat Quality:
Two survey visits per month (April – September) plus three static detector locations per transect. Static bat detector data to be collected on 5 consecutive nights per month (April – September).
Cost: From £5,000*
*NOTE: The costs quoted above may vary for larger or more complex sites or for greater travelling distances. All quoted figures are exclusive of and are subject to VAT.
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What if foraging or commuting bats are found on-site?
Once all required information has been gathered it is then possible to predict likely impacts as a result of the proposed works. Identified impacts should be avoided if possible (e.g. retaining a habitat feature rather than removing it).
However, if this is not possible it will be necessary to devise appropriate mitigation measures to minimise any unavoidable impacts. These mitigation measures may include reducing the area or length of habitat feature to be removed or incorporating a bat-friendly lighting design.
Where there are permanent, ongoing impacts identified (e.g. loss of a habitat feature) it will be necessary to provide appropriate compensation measures. These compensation measures may include the provision of a replacement habitat feature and enhancement of existing habitat features on-site.