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

09 Feb 2022 | No. 2022-06

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.

Five of the 11 species of bat had not been recorded previously in Guernsey, and included Serotine, Whiskered or Brandt’s bat, Leisler’s bat, Common Noctule and Lesser Horseshoe bat. Serotine was also new for Alderney and Sark. A new species of bush-cricket, Large Conehead, was also found on Guernsey, Alderney and Lihou, which is the first record of this species in the Channel Islands.

Sarah Allez, the Bailiwick Bat Survey Coordinator at La Société said, “Undertaking such a large survey of the islands was only possible because of the large numbers of volunteers who put out detectors for us. The enthusiasm shown by volunteers has been amazing and the survey has really highlighted how some species rely on buildings for safe roosting areas and natural habitats for feeding.”

Julia Henney, Biodiversity Officer at ACLMS said, “Such a widescale survey has given us an insight into how this often overlooked group of nocturnal mammals uses Guernsey’s built and natural environment. With three more years to go we will have a comprehensive understanding of the habitats that are important for all the bat species that occur in the islands.”

Dr Phil Atkinson, lead scientist on the project, said, “The current dataset of 710,260 bat recordings has been very valuable in adding to our understanding of patterns of occurrence and activity of bats across the Bailiwick of Guernsey, but it also adds to our understanding of some other species groups that were recorded as ‘by-catch’ during bat surveys, and shows the power of citizen science. My thanks go to the 200+ volunteers who dedicatedly deployed the detectors, without which this project would be extremely difficult to carry out. I look forward to seeing what we might discover next year.”

The full report can be read here

Contact Details
Paul Stancliffe
 (BTO Media Manager)
Mobile: 07585 440910
Email: press [at] (subject: News%20release%20enquiry)

Mike Toms (Head of Communications)
Mobile 07850 500791
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Images are available for use alongside this News Release. These can be downloaded from this link for which you will need to enter the password Bailiwick202206 alternatively, please contact press [at] quoting reference 2022-06

Notes for editors
The BTO is the UK's leading bird research charity with recognised expertise in bird monitoring, but the breadth of its knowledge means that the BTO can make valuable contributions to monitoring other taxa. A growing membership and up to 60,000 volunteer birdwatchers contribute to BTO's surveys, collecting information that underpins conservation action in the UK. BTO maintains a staff of 100 at its offices in Thetford, Stirling, Bangor (Wales) and Belfast (Northern Ireland), who analyse and publicise the results of surveys and projects. BTO's work is funded by BTO supporters, government, trusts, industry and conservation organisations.

ACLMS are the Agriculture, Countryside & Land Management Services of the States of Guernsey. It is responsible for the implementation of the Strategy for Nature and works with a range of partners to do this through the Biodiversity Partnership Group.

La Société was founded in 1882 to encourage the study of the history, natural history, geography and geology of the Bailiwick of Guernsey, the conservation of the Bailiwick’s natural environment and the preservation of its historic buildings and monuments.

The Guernsey Biological Records Centre (GBRC) is run by Environment Guernsey Ltd. on behalf of the two partners; La Société and the States of Guernsey. Data is submitted on a regular basis from Guernsey residents, keen naturalists, researchers and visitors from a variety of sources, including social media. The GBRC is actively involved in local, interisland and international conservation projects. It collates, manages and stores data that describes our local biodiversity and forms an evidence base to which decision makers can refer when making decisions which may impact on wildlife or wildlife habitat. 

The Biodiversity Partnership Group is made up of local environmental NGOs and States of Guernsey Agriculture, Countryside and Land Management Services. The Biodiversity Partnership advises on, and supports the implementation of, the Strategy for Nature.

The BTO, ACLMS and La Société would like to thank all the volunteers who took part in Bailiwick Bat Survey in 2021 and the landowners that gave volunteers access to their land. Thanks also goes to the Guernsey Museum at Candie, the Guille-Allés library, the Alderney Wildlife Trust and Sark School who all hosted bat detectors for the project and to  the many other individuals and organisations such as the Bat Section of La Société for their help and support of this project across the islands.

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