First year of a four-year survey discovers five new species of bat for the Bailiwick of Guernsey

First year of a four-year survey discovers five new species of bat for the Bailiwick of Guernsey - BTO

The most extensive bat survey carried out by citizen scientists in the Bailiwick of Guernsey using remote automated recorders has found several new species of bat and a new species of bush-cricket for the islands of Guernsey, Alderney, Herm and Sark, as well as collecting almost three-quarters of a million sound recordings of bats, small terrestrial mammals, bush-crickets and audible moth species.

Bats are a poorly understood component of the Bailiwick of Guernsey’s fauna, despite making up more than half of the terrestrial mammal species. Guernsey’s Strategy for Nature provides a clear direction to establish baselines for key biodiversity groups to provide government, other policy makers and practitioners the information required for good decision making. Learning more about the numbers and species of bats locally contributes to this, as they are key species for indicating the condition of the islands’ environment.
This research is being carried out through the Bailiwick Bat Survey: a four-year partnership project between the British Trust for Ornithology (BTO) and the States of Guernsey’s Agriculture, Countryside and Land Management Services (ACLMS) with coordination by La Société for the 2021 survey. Over 200 volunteers signed up to survey one or more of the 360 500x500m survey squares and borrow a detector for 4-6 nights from one of our Bat Centres. Working with this network, static acoustic bat detectors were deployed during 2021 over a long survey season (April to October). A total of 2,221 complete nights of recording effort was achieved across 611 different locations, providing the first extensive baseline data for bats for the islands. The Alderney Wildlife Trust and La Société Serquaise organised the surveys in Alderney and Sark, and the Guernsey Biological Records Centre hosted the website and will be the repository of the data.

Over 1.5 million sound recording files were collected by volunteers. These were initially fed into the BTO’s Acoustic Pipeline, where they were automatically identified to species using machine learning. Following an additional process of manual verification, these were found to include 710,260 bat recordings, and 8,211 small terrestrial mammal recordings. In addition, several species of bush-crickets and audible moth species were recorded, revealing the presence of 11 bat, 5 small mammal, 6 bush-cricket and 2 audible moth species.