A Nathusius’ pipistrelle which had been ringed in Latvia was caught by members of Essex Bat Group (EBG) at Chigborough Lakes on Friday, 1st September. The bat was ringed at Riga, Latvia (on the Baltic coast) on 23rd August 2016.
The trapping session at Chigborough was carried out under license as part of a national study of Nathusius’ pipistrelle. This species migrates from northern Europe to parts of western and southern Europe each autumn and returns in the spring. It has long been suspected that this species migrates to Great Britain as part of this annual movement, largely on the basis of past records from offshore oil rigs and gas platforms in the North Sea.
This is the 5th re-capture of a Latvian or Lithuanian ringed bat in south east England during the first four years of the national study and the first to be captured in Essex. The capture of a confirmed migrant on the north side of the Blackwater is perhaps significant. The Dover Straits are the narrowest crossing point between Britain and Europe but records from offshore installations, including recent records from offshore wind farms, suggest that bats also cross the much wider North Sea. So it is quite likely that our ringed Latvian bat had recently flown in across the southern North Sea. Whatever the route, it had flown to Chigborough Lakes from Riga. This is a straight line distance of approximately 1,000 miles (1,600 km), although of course the bat will have flown further than that to get here. .
It is hoped that proving migration between Britain and continental Europe and identifying migration routes will mean that migrating bats can be properly taken into account during the planning and operation of offshore windfarms, which may present a threat to migrating bats.