The largest common pipistrelle bat winter roost in the UK has been found at Seaton Delaval Hall in Northumberland, revealing previously unknown information about the bats’ hibernation habits.
Sixty-one pipistrelle bats were recorded in stone crevices and in the arches of a balcony at the hall earlier this year.
Significantly, the discovery also turns on its head ecologist’s long held belief that the pipistrelle prefers to hibernate in very dark, damp conditions, with these bats found hanging out in a dry, arid, relatively well-lit area of this grand 18th Century building.
Tina Wiffen, bat ecologist said: “We discovered the bats when we were undertaking an ecological survey to assess the possibility of introducing new art and visitor information installations into the Central Hall of the building – a project being supported by the National Lottery.
“On finding the bats, we conducted a formal survey and at least 60 bats were counted in February and 61 in early March – with more visits then needed for verification. It’s likely that even more bats are here, hidden in deeper crevices.
“As a result the site will now be even more closely managed and monitored to ensure that the bats can continue to use the hall as their winter roost.”
Bats have made their home at Seaton Delaval for hundreds of years. It is widely thought that bats first came to roost at the Hall after it was ravaged by fire in 1822 and left exposed to the elements for around 40 years before being reroofed in the latter half the century, making the space warmer and drier, but with the bats still able to gain access through the crevices in the stonework.
David Bullock, Head of Nature Conservation at the National Trust visited the Hall recently to verify the findings. He said: “I’ve never encountered hibernating pipistrelles in such numbers before. The cavities in the stones in Seaton Delaval Hall’s Central Hall provide one of the few known hibernation sites of what could be hundreds of bats.
“Most bats like cool, moist and dark hibernation locations. In contrast, the pipistrelles residing in the Central Hall were in light and dry crevices. We would never have thought to look in these conditions. That says to me that we’ve been looking in the wrong places, and we don’t actually know if they’ve changed their behaviour.”
The National Trust’s team at Seaton Delaval will now use more of the National Lottery funding to undertake further surveying work to understand more about how the bats interact with the spaces in the Great Hall so that it can protect and look after the pipistrelles before any of the planned repairs and conservation work starts later this year.
Header image: National Trust.