Use of Infra-red during bat surveys

During the summer of 2022, E3 Ecology was commissioned to undertake bat surveys of an agricultural barn on the outskirts of Newcastle. Based on an initial daytime bat risk assessment survey, the building was considered to be of only low suitability to support bat roosts, due to a general lack of suitable roosting features. In accordance with Bat Conservation Trust (BCT) Survey Guidelines, one dusk bat presence/absence survey was completed to assess how bats might be using the barn.

During the survey, bats were observed to be flying in and out of the barn, using it as a sheltered foraging area. However, it was noted that more bats were seen leaving the barn through the large doors than those which entered from the other side, meaning that bats were originating from a roost within the building as well.  As the barns were very large and dark internally, locating the exact roosting point that the bats occupied during the daytime presented a challenge. A further dusk survey was required in accordance with BCT guidelines (as roosting bats had been confirmed as present) and this survey would gather additional information with which to support a planning application and bat licence application with Natural England.

During the further survey, E3 used infra-red video cameras and lights to record the interior of the barn. This wavelength of light is invisible to humans and most other mammals, but this equipment allows us to watch and record bat activity in total darkness, thus not disturbing the bats’ natural activity with additional lighting. Using this technology, E3 was able to pinpoint the exact roost location and use this information to support the planning application. The roost was associated with a profile metal sheeting roof and supporting beams, which is a relatively unusual location in which to find a roost, especially in a modern agricultural building.  This demonstrates the usefulness of using modern technology during bat surveys to provide accurate, reliable and robust results, thus minimising delays if bats were unexpectedly found later down the line in the development process. This allows all necessary procedures to be followed and reach a successful outcome for wildlife and development.