In 2014 we deployed bat detectors on the islands of Skomer, Skokholm and Ramsey, off the west coast of Pembrokeshire, Wales. The islands are between 0.8 km and 2.6km from the mainland.
The aims were to increase knowledge of the bat fauna and investigate evidence for migration through the identification of changes in seasonal bat activity. The detectors were set to survey from half an hour before sunset to half an hour after sunrise from spring to autumn, the most active period for bats and the peak migration seasons.
A minimum of nine species of bat were recorded on Skomer and Ramsey, and seven on Skokholm. The pattern of activity suggested that some species roost on the islands, and that use by dispersing and/or migrating bats also occurs. A peak was observed in the activity levels of Leisler’s bat, with a higher number of calls recorded in autumn than at other times.
Records of greater horseshoe and barbastelle bats on the islands were unexpected, as there is limited evidence of sea crossings in these species from other parts of the UK.
The full report is available below.
We would like to extend our thanks to the RSPB and South West Wales Wildlife Trust and their respective wardens for allowing and helping us to complete this project on the islands.