Devon Bat Survey – Project Summary
Ruth Testa, Devon Wildlife Trust

Since receiving the grant, the Devon Bat Survey has made significant strides in monitoring and understanding bat activity across Devon, particularly that of the greater horseshoe bat. Using SM4 detectors and new microphones, winter research surveys first explored how these bats use the landscape during colder months. Although some data was lost due to battery issues in low temperatures, the project collected substantial recordings that raised intriguing questions about winter bat behaviour.

The main citizen science initiative — the 2018 Devon Bat Survey — proved hugely popular, with 728 participants and over 900,000 sound files collected by the end of the season. Most participants reported positive experiences and surprising diversity in local bat species — sometimes recording up to 12 different species per survey square. A total of 3,376 greater horseshoe passes were recorded at 270 locations, including two newly identified hotspots, which are now priority areas for further research.

Volunteers played a key role, assisting with the manual verification of species identifications and receiving training in acoustic analysis tools like AnalookW and Kaleidoscope. Verified records are being added to the Devon Biodiversity Records Centre and are already informing local planning policy and conservation strategies.

The winter detector surveys (2017/18 and ongoing 2018/19) revealed unexpected levels of greater horseshoe activity well beyond known hibernation roosts and at low temperatures. This prompted a second passive monitoring study, deploying 20 static detectors around a known roost. The data will be compared with habitat and weather variables to refine conservation advice for key roosting and feeding areas.

The project is enhancing scientific understanding, contributing to local planning and land management, and engaging communities in meaningful wildlife monitoring — laying the groundwork for stronger, evidence-based conservation of Devon’s bat populations.