A BUMPER sized baby bat has set a record among its endangered nocturnal colony in Stroud.

The juvenile, a rare Greater Horseshoe, was the biggest measured by expert Dr Roger Ransome since he began studying the bats at Woodchester Mansion over half a century ago.

“One of the female juveniles had a forearm of 60.4mm which is a record for Woodchester over my research period – 1956 to date,” said Dr Ransome.

“The previous best was 59.2mm while the average is 56.2mm for females.”

Dr Ransome’s Greater Horseshoe study is the longest of a mammal anywhere in the world by a single person.

This season his team have caught and processed 202 Greater Horseshoe bats.

“There were 82 surviving juveniles present from 89 births this summer,” Dr Ransome said.

The Grade One listed Victorian Gothic mansion, which was abandoned unfinished in 1873, has colonies of protected Greater and Lesser Horseshoe bats, as well as Pipistrelles, Long Eared and Serotine bats.

Visitors to the mansion, which is now open six days a week, can see them via a special bat cam. It uses infra red cameras to relay live pictures to an observatory.

Mansion manager Hannah McCanlis said 2014 had been an amazing year for the bat colonies.

“This is shown in their growing numbers. The Bats are nearly back to the bumper figures of the 1980s before the terrible winters,” Ms McCanlis said.

“Everyone at the Woodchester Mansion Trust was thrilled to learn that not only are the colonies numbers improving year on year but that they are growing larger.”

Ms McCanlis said the trust believed the tropical summer just experienced was partly why the bats were thriving.

“The better the weather the better the opportunities they have to feed well land grow big and strong,” she said.

Woodchester Mansion Trust, an independent charity, opens the buildings’ doors to the public for them to gain a unique view of the stonemason’s craft through the incomplete structure.

The surrounding parkland is owned and administered by the National Trust.