Ecologist Rachel Taylor will present a talk to the Welsh Bat Conference at Stackpole, Pembrokeshire, on the subject of BSG Ecology’s Bat Migration Project (2012-2014). Rachel’s talk is entitled “Bats on the Pembrokeshire Islands and an overview of BSG Ecology’s Bat Migration Project.” An outline of the talk is as follows:
There is currently little information available on the migratory behaviour of UK bats, although four species that are known to undertake long-distance migration within Europe occur in the UK, with three of these breeding here (noctule, Leisler’s bat and Nathusius’ pipistrelle).
During 2012-2014, BSG Ecology carried out a number of studies to collect evidence that might indicate bat migration was occurring into and out of the UK. These included deployment of bat detectors at nine locations on the UK coastline, and on two offshore ferries in the southern North Sea as well as stable isotope analysis of fur samples from 25 Nathusius’ pipistrelles caught in the UK.
Our bat detector studies showed clear seasonal patterns of occurrence for Nathusius’ pipistrelle, with activity peaks in spring and autumn that were strongly indicative of migration. The stable isotope analysis suggested that at least 40% of the bats had moved a long way since moulting the previous summer, and may have come from northern or eastern Europe outside of the UK, with some bats potentially resident in the UK.
In 2014 we deployed bat detectors at three Pembrokeshire islands; Skomer, Skokholm and Ramsey Island, all of which are managed by nature conservation organisations (either by The Wildlife Trust of South and West Wales or RSPB Cymru). The islands were previously all thought to be relatively unsuitable for bats due to a lack of foraging and roosting habitat, shelter and their distance from the mainland but the results of the study were surprising.
We recorded a high species diversity, including a number of species that had not been recorded on any of the islands previously. These included two species, greater horseshoe and barbastelle, that are rare and have not, to our knowledge, been recorded regularly crossing the open sea before. Greater horseshoe bats were recorded at all islands with a peak in detection rates in September, while barbastelle was recorded at Skomer and Ramsey. The records suggest that this is regular and predictable behaviour and that bats may be commuting to the islands regularly. The timing of bat records also indicates that up to five species could be roosting on the islands, either in buildings or sea caves.
A peak of activity was also observed in the late summer/autumn for species that are known to be long distance migrants in Europe, with several records of Nathusius’ pipistrelle and Leisler’s bat in the autumn and noctule records peaking in August and September. The timing of the records may indicate migratory behaviour, post-breeding dispersal of bats, or bats exploiting a seasonally abundant prey species.
The Pembrokeshire bat report is available below. Rachel’s talk will take place on either Saturday 6th or Sunday 7th June (the programme is yet to be finalised). More details on the conference can be found on the Bat Conservation Trust website.