"We had better whisper from now on, and use the torches sparingly," advised Dr Ruth Warren, a mammal expert with the Countryside Council for Wales (CCW). One or two of the bats were flying around us, presumably aroused from their snoozing. We didn't want to wake up any more of them.
Underneath a former stately home in North Wales, long-since-abandoned boiler rooms have become hearth and home to no fewer than 579 lesser horseshoe bats during autumn and winter. As we strained to look up to the roof, the resting bats were a sight to see. Hundreds of them, all black, with their wings folded in, were hanging down limply from the roof. One neck-craning look and we were off, down to the hi-tech end of the cellar where there is a permanently installed computer.
The cellar has an automatic bat- counter at its single entrance, through which all the bats fly in and out. By breaking its infrared beams, each bat is counted coming or going by the computer wired up some yards away. The counter has been in operation for only a year or so but already, says Ruth Warren, it is starting to provide invaluable information about the bats' activities. Their patterns are also being related to temperature measurements, providing much-needed information about these poorly known mammals and thereby helping in their protection.
Ash-grey above and pale buff below, lesser horseshoe bats - named after a horseshoe-shaped flap of skin on their faces - have a wing span of up to 9.5in and a body and tail length of about 2.5in. They weigh as little as a fifth of an ounce. Each female gives birth at the end of June to a single youngster, which then suckles for four or five weeks. During September, the maternity roost disperses. Nowadays, around 150 lesser horseshoes hibernate for the winter at the cool end of the cellars here, whereas the maternity roost stays in the warm. In agreement with the mansion's owners, CCW pays the heating bill.
When the coal-fired boilers were in use, the bats roosted in the roof of that part of the cellar.
"They prefer warm sites for their maternity roosts, but their droppings were falling on the boiler," said Ruth Warren. "So greenhouse radiators were installed to encourage them to relocate." They did so.
In the UK, lesser horseshoes are confined to south-west England and Wales, having died out in the Midlands and south-east England. According to the published Action Plan for the conservation of this protected species, there may be 14,000 left in Britain. About 230 summer roosts and 480 winter hibernation roosts are known.
But bats - and their essential roosting sites - are highly vulnerable. Deterioration of buildings they are using, renovation of old buildings, barn conversions, the blocking up of old mines and caves, disturbance at their roosts, and losses of feeding habitat such as woodland, wetland and hedgerows, are all contributory factors.
The bats here are well positioned. From these cellars, they have easy access to woodland within 20 yards of their exit - this former stately home is surrounded by park land. No one knows how long the bats have been here. According to Ruth Warren they were discovered in 1962, when there were perhaps 200 of them. But one thing is sure: with the CCW watching over them, their future has never been brighter.Reuse content