© Camilla Mitchell

© Keith Cohen

One of the rarest mammals in Britain has been found in Wiltshire, according to a University of Sussex professor.

The Alcathoe bat was first found in Britain in 2010 and, despite a lot of work to try and find it, sightings have only been made in North Yorkshire and a small area of Sussex and Surrey.

This is why the discovery — made outside a cave near Bradford-on-Avon — has so excited Professor of Environmental Biology Fiona Mathews, who has, with the Wiltshire Bat Group, been monitoring the area for many years.

Local bat workers Keith Cohen and Danielle Linton, who captured the bat, said: “We have been trapping bats at these Wiltshire swarming sites for many years.

“This bat looked distinctly different from those we usually catch, so it was very exciting in case it could be an Alcathoe bat. Luckily we very soon also caught a whiskered bat, which is the species it looks most like, and could compare them side-by-side."

Professor Mathews said: “It’s incredibly exciting for the Alcathoe bat to have been found at this site.

“In my recent report with the Mammal Society A Review of the Population and Conservation Status of British Mammals - JP025, I classified it as one of the species in most urgent need of research. We quite literally know almost nothing about it.”

The female bat, which had just finished breeding, was found at a swarming site in early autumn last year by workers who thought it looked unusual and sent dropping samples to Professor Mathews to test.

She explained: “Some types of bats go to swarming sites late at night after feeding. They’re almost like nightclubs for bats.

“Tens or even hundreds of bats can turn up but behaviour is very sporadic, so any given site could have hundreds of bats one night and absolutely none the next.

“We monitor these sites carefully and catch bats using mist nets, which are like large fishing nets. The bats are then removed by specially licensed bat workers, checked and released unharmed.

“In this instance, workers thought the bat looked a bit unusual and sent dropping samples to me at Sussex where my company, Ecotype Genetics, confirmed the identity of the species using DNA analysis.”

There are currently 18 species of bats in the UK, of which 17 are known to breed here.

While the population size of the common pipistrelle, which is found throughout the UK, is thought to be close to 2 million, the population of Alcathoe bats is likely to be just a few thousand individuals, and breeding has been confirmed in only one small area in the south-east of England.

Professor Mathews said: “The Alcathoe bat looks very similar to two other related species, the whiskered and Brandt's bat species, so it is possible that people misidentify it. Indeed it was only separated as a distinct species in Europe in 2001.

“The areas where it has been caught so far usually have old oak woodlands nearby, which is not the case with the bat we’ve just found.

"This only serves to illustrate exactly why we need to do more research about the species to understand its needs, and how we can protect it."