Drum study sheds light on sleeping secrets of bats

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A study carried out at the National Trust for Scotland’s Drum Castle has shed light on the mysterious winter hibernation behaviour of bats.

The study, which was carried out over the winter by expert conservationists from the NTS, looked into the fascinating sleeping habits of the mammals.

Very little is known about how much disturbance bats can tolerate.

Toni Watt

Trust ranger for the North East, Toni Watt, said: “Bats are mysterious creatures and there is still a lot we don’t know about them, a lot still to be discovered.

“In the UK all our bats hibernate. This is partly because they all feed on insects which are in short supply in the cold winter months, and partly because they are so small that they lose body heat rapidly.

“At Drum the bats hibernate in deep cracks and crevices in the tower cellar and each year we carefully count the number of bats we can see for the National Bat Monitoring Programme. This has to be done carefully and with a licensed bat worker as any disturbance could cause the bats to wake up and use up valuable energy supplies.

“As many of you will be aware there has been a lot of work at Drum Castle over the winter, re-surfacing the courtyard and the main drive and we wanted to see if the work disturbed the bats in any way.

“Very little is known about how much disturbance bats can tolerate while they are hibernating and we acquired a licence from Scottish Natural Heritage to see if the bats moved or behaved any differently while the work was taking place.”

The surveying of the bats began in autumn last year and continued through the courtyard re-surfacing work.

Toni continued: “We counted the bats and marked the crevices they were in with chalk so we could see if they moved.

“I also went into the hibernaculum while the work was on going to see if the bats became agitated or moved at all. But amazingly considering the noise and vibrations produced by the heavy machinery, the bats were not disturbed and numbers of bats in the hibernaculum slowly grew into winter and have only now started to dwindle as we move into spring.

“We are now keen to see exactly when the bats will leave to start roosting in their summer roosts and for the females this will be their maternity roosts.”