There is currently considerable uncertainty as to the extent to which bats migrate in and out of the UK from Continental Europe, although many experts in UK bat ecology consider that some degree of migration occurs. Small scale research studies, development-related survey at coastal sites and records of bats on vessels and offshore oil rigs have provided indications that migratory movements occur in spring and autumn. However, this gap in current knowledge does not appear to be being addressed through strategic studies.
In 2012 BSG Ecology undertook a pilot study to determine if pulses of bat activity indicative of migration could be detected at a site on the east coast of England. Dungeness, Kent, was chosen for the initial work. The site was selected due to its geographical location, physical characteristics (open and exposed with few roosting opportunities) and due to the presence of the Bird Observatory, which has a permanent ecologist, David Walker (who helped with the work).
Dungeness is approximately 40km west of the French coast, and bats (and birds) moving between continental Europe and the UK would minimise time spent over the sea if crossing the English Channel at this location. The work was led by Laura Grant, Senior Ecologist at BSG Ecology’s Oxford office.
In order to obtain baseline information, a fixed point static detector was used to remotely monitor bat activity at the Dungeness Bird Observatory. The detector was deployed between early April and early October 2012, and set to record between half an hour before sunset and half an hour after sunrise. It was protected by a waterproof ‘pelicase,’ and attached to a 12v external battery to prolong recording time. The microphone (required to detect the bat echolocations) was housed within a section of piping in order to waterproof the unit. The resulting data was analysed using Analook software.
Information gathered by the Bird Observatory, including daily (prevailing) weather conditions and observations of bird migration was provided for context.
During the survey period a minimum of 8 bat species were recorded at the Dungeness Bird Observatory. These were three species of pipistrelle (common pipistrelle, soprano pipistrelle and Nathusius’ pipistrelle), noctule, Leisler’s bat, serotine, at least one species of the genus Myotis, and a long-eared bat species.
Conclusions and Next Steps
The study found that for Nathusius’ pipistrelle there was a notable increase in bat passes per hour in September. This corresponds with the period in which this species is considered to head south-west from Scandinavia to overwinter in warmer climates. Increased activity recorded in May appears to correspond with return passage of Nathusius’ pipistrelle back to continental Europe to breed. For other bat species there was no clear indication of migratory movements.
The Dungeness pilot study therefore suggests that there is evidence of migratory movements of bats into and out of the UK. BSG Ecology is currently considering how to progress further research in 2013.
For a full PDF copy of the report, which includes detailed methods and results sections, and a short review of current evidence of migration in UK bat populations, please contact us at:
For more general advice on bats and bat survey, please contact one of our offices.