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Rare bat travels from Latvia to Hertfordshire

Friday 1st September 2017

Nathusius’ pipistrelle bat (c) Daniel HargreavesNathusius’ pipistrelle bat (c) Daniel Hargreaves

Eight Nathusius’ pipistrelle bats have been recorded at Stocker’s Lake Nature Reserve in Rickmansworth, with one identified as flying all the way from Latvia. Stocker’s Lake Nature Reserve is owned by Affinity Water and managed by Herts and Middlesex Wildlife Trust

The bats were trapped and released along with three other species, 55 bats in total, as part of the Bat Conservation Trust’s National Nathusius' Pipistrelle Project, a collaboration with bat conservationist Daniel Hargreaves. The project launched in 2014 to improve understanding of the ecology, current status and conservation threats for Nathusius' pipistrelles in Great Britain.

Experienced bat worker Patty Briggs organised the survey team last week at the reserve in the Colne Valley. The team used four harp traps, devices which look like a large harp with a catching bag underneath, together with acoustic lures which emit ultrasonic calls to attract the bats. The Nathusius’ pipistrelle bat, larger than common and soprano pipistrelles the most commonly found in the UK, has chestnut brown fur and weighs around 8 grams.

Dr Katherine Boughey, Head of Monitoring and Science from Bat Conservation Trust said: “The National Nathusius' Pipistrelle Project has only recorded four other long distant migratory records – one bat ringed near Bristol was rediscovered in Holland, a bat from Latvia was recaptured in Sussex and two bats ringed in Lithuania were recaptured in Kent.

“This latest record is a total distance travelled of more than 1494km, which is an astonishing feat for a tiny mammal, not only in regards of the distance travelled but in navigating the English Channel in the dark. The hard work of volunteer surveyors across the country is giving us a great insight into this bat’s migratory behaviour”.

Patty Briggs said: “We are delighted that our survey was so successful. Relatively little is known about the Nathusius’ pipistrelle’s migration route to Britain so finding eight at Stocker’s Lake was fantastic and capturing one that had already been ringed in Latvia was an incredible piece of luck and a real asset to the project. Very few Nathusius’ pipistrelles are ringed each year so the chances of a recapture are miniscule”

Louise Sleeman, the Trust’s People and Wildlife Officer for Affinity Sites said: “The Trust works hard to ensure that Stocker’s Lake is a great place for wildlife. We have run several bat events at the reserve and know that Daubenton’s, common and soprano pipistrelle and noctule bats already make good use of the site. We are thrilled to hear that this latest survey has been so fruitful and look forward to continuing to work with Patty on the on-going surveys, contributing to the Bat Conservation Trust’s data on this species, as well as our own records, to continue to improve local nature reserves for wildlife”.

Nathusius’ pipistrelle bat long distant migrants (c) Daniel Hargreaves