Big Scilly Bat Survey
Bats on Scilly
The Big Scilly Bat Survey was an innovative project led by the Isles of Scilly Wildlife Trust and the Isles of Scilly Bat Group, and funded by the Isles of Scilly National Landscape and supported by Bat Conservation Trust. We used state of the art technology developed by the British Trust for Ornithology (BTO) to help answer a few questions, including what bat species live on the islands, which species are resident, which are seasonal visitors and the favourite foraging grounds on different islands. We want to help bats thrive on Scilly, so understanding their ecology is the first step.
Read the 2023 Report
Read the 2022 Report
The Big Scilly Bat Survey ran over three years, from spring-autumn 2022-2024. We were delighted to be working with land managers, farmers and businesses across the archipelago. Local volunteers and staff worked together to put out the static acoustic monitors (SAM) over six nights. The stationary detectors recorded data constantly, listening out for pips, squeaks, clicks, chips and chatter, most of which are beyond human hearing. Once the sound files were downloaded and analysed, we could build an island-wide picture of the secret world of bats and understand more about their behaviour. Not only that, but early results allowed us to 'listen in' to other species, too, and we quickly picked up the sounds of Scilly shrews and crickets on our detectors.
What's involved?
The Isles of Scilly Bat Group recruited members from across the islands to take part in our 500m² surveys. Each volunteer installed the SAM within a 500m² square for a total of four days and nights, which recorded constantly. All five islands were divided into squares, with the idea being to survey each square. The volunteer then downloaded the sound files onto their laptop or computer and sent it to the BTO pipeline for analysis, a process that sorts the files into what it thinks the species are. The pipeline dramatically reduced the amount of analysis needed for the project, but the data still needed to be audited by manually analysing some sonograms at the end of the season. Like us, the technology is also learning. For example, the pipeline had never come across a Scilly shrew before and believed them initially to be Noctule bats (which echolocate at 20-45kHz), however with the shrew files now added to the configuration files, there was less chance of that happening.
At the end of each year, we analysed all the results with the help of volunteers and Bat Conservation Trust and started to build up a coherent picture of what bats are present on Scilly, and what we can do to help them. The project ran for three years, giving us an invaluable insight into this secret night-time world.
Bats are fascinating and largely misunderstood creatures. We know that on Scilly, seven species of bat have been recorded, however only three are resident: the common pipistrelle, soprano pipistrelle and brown long-eared bat. This research will play a vital role in understanding more about them and inform our conservation efforts to help them.
There's lots you can do to support bats in your community, like encouraging an abundance of insects, reducing light pollution, adding a pond to your garden or cutting back on pesticides. Download our Stars of the Night Wild About Gardens booklet to find out more.