Listed Building Renovation and Bats – How Anabats Help!

Listed Building Renovation and Bats – How Anabats Help!

Ecological Assessment

A Grade II listed farmhouse in Edenbridge, Kent, due for renovation works, was internally inspected for the presence of roosting bat species in the summer of 2015. Two brown long-eared bats (Plecotus auritus) were observed roosting within the void during an internal inspection.

Bat Surveys

As a result of the initial assessment further surveys to support a licence application were recommended including the use of a remote recording device, the ‘Anabat express’. Anabat remote bat recording devices have proved to be an essential piece of equipment for ecologists, providing an insight into otherwise unknown patterns of activity in bat species.

An Anabat Express remote recording device was placed within the void to record any bat activity over a period of 10 days.  Continuous bat calls from brown long-eared bats were heard throughout the night as well as periods of intense calling. The level of calls recorded suggested a greater number of bats using the void than were seen during the internal inspection.

Calls were recorded regularly throughout the night suggesting the void was being used as a maternity roost, with mothers returning frequently to feed pups.

Bat mitigation - Anabat sound files The Ecology Partnership
Anabat sound files

Picture above showing anabat sound files, here activity recorded pre emergence in the evening.

Maned emergence surveys identified how the bats were exiting the building, with the brown long eared bats emerging from the bottom of the eastern chimney stack.  Common pipistrelles were also recorded emerging from under the hanging tiles located across all aspects of the building.

bat mitigation
Two long eared bats recorded within the void at the time of the survey.


During the manned dawn re-entry survey, very little bat activity was observed around the house during the opening hour and a half of the survey. From the data collected from the Anabat Express it was clear that the peak of activity within the void around dawn was at approximately 4am.  After an hour and a half of limited activity from pipistrelle species, at 4am, approximately 12 brown long-eared bats were observed swarming around the base of the chimneystack and re-entering the void beneath lifted tiles. This coincided with approximately 10 common pipistrelles swarming on the southern side of the building, repeatedly landing on the hanging tiles before re-entering the crevice habitat beneath them.

The Anabat Express installed within the roof void supplied key supplementary data to the usual manned external dusk and dawn surveys. Insight into activity levels within the void and the times of peak activity.

Bat Mitigation Strategy

A full mitigation strategy was devised by The Ecology Partnership including a detailed method statement of works, the erection of bat boxes within adjacent trees and the retention of the roof void as a bat roost post development, including bespoke bat access points around the base of the chimney stack using moulded lead flashing. A European Protected Species (EPS) licence issued by Natural England was applied for and granted.



bat mitigation
Hiding bat during the hanging tile soft strip. This highlights how bats can even squeeze into the smallest of spaces.





A soft strip of the hanging tiles was undertaken over the winter months to avoid summer roosting bats. However, five common pipistrelles were found roosting beneath various hanging tiles during the soft strip. These individuals were captured and handled by one of The Ecology Partnership’s licenced bat ecologists and transferred safely to one of the Schwegler bat boxes suitable for hibernating bats.

bat mitigation
Stripped building, tiles all retained for replacement.



Through The Ecology Partnerships suite of surveys and the use of the Anabat Express within the void the brown long-eared maternity roost and common pipistrelle day roost were successfully and correctly identified. Through the development of the mitigation strategy and the successful application for a licence of Natural England works on site were conducted legally and as planned without a negative impact on the nature conservation status of brown long-eared bats and common pipistrelles.

To discuss a bat survey or the production of a bat mitigation strategy, please email us or call us on 01372 364 133 or use our enquiry form below.


Visit also:

Ecological Mitigation

Bat Surveys

Bat Mitigation Project – Shwegler Bat Boxes Installation