The combined forces of technology and dedicated volunteers are being deployed to eavesdrop on the after-dark activity of bats at Winspit Quarry caves in Dorset.
The National Trust, working closely with the Dorset Bat Group, has mounted bat detectors on three poles at the quarry to record the ultrasonic clicks, squeaks and calls of the bats, which are largely at frequencies higher than a human can hear.
Once an industrial workplace, Winspit is now a habitat for wildlife
Nationally-important ‘swarming’ site for bats
Late summer and autumn is when hundreds of bats gather along the coastal cliffs in Purbeck, with Winspit being a nationally-important ‘swarming’ site for bats.
Purbeck is home to 15 of the 17 UK species of breeding bat. Not all bat species swarm, but those that do fly from far and wide to a specific area to mate and select hibernation sites.
The detectors will be in place until November 2024 and then the British Trust for Ornithology will help analyse the results using specialist technology.
A juvenile male common pipistrelle bat which is the UK’s smallest and most common bat
“Help us learn more”
National Trust ecologist, Michelle Brown, said:
“Most of the bat activity is under cover of darkness, so it’s difficult to know how many bats are using the caves, and what species they are. The detectors will help us learn more, giving a broad picture of the range of species that pass by.
“It isn’t an exact science as some species have sounds that are too similar to distinguish them from each other, but it will give more information than we’ve been able to gather before.”
The detectors will back up the monitoring that volunteers from the Dorset Bat Group have been doing for the past 12 years. Working under licence, they trap bats in nets, measure them and record their size, weight and sex.
The bats are then ringed on their forearms, with previous tags revealing that some of them come to Winspit from more than 16 miles away.
Common pipistrelle bat in flight
Autumn swarming
Michelle said:
“We are hugely grateful to the bat group for all their hard work, which often involves being out on the windswept coastline in the cold and dark!
“Our work simply could not be done without the support of volunteers across Purbeck who help out with all aspects of wildlife monitoring and countryside management.”
Michelle also added a note of caution for anyone hoping to see a mass of bats:
“Autumn swarming is the term used to describe bats that gather at key locations to mate. We have different species swarming at different times, and the activity takes place in waves between dusk and about 4 am.
“So there’s not a ‘swarm’ as such to see. Winspit Quarry is closed to the public for safety reasons, so we’d ask that people don’t go down there, especially at night.”
Natterer’s bat – a medium-sized bat with fairly long ears and a bare, pink face
Devise a strategy for bats
Bat studies and other initiatives are also taking place at inland quarries across South Purbeck.
The National Trust says that the aim is to put all the findings together then devise a strategy for bats across the region.
In the future, this could mean connecting local habitats to help the bats spread and thrive, managing the land to increase insect numbers to feed the bats, improving existing roosting sites and creating new roosts.
Brown long-eared bats – medium sized bats with huge ears!
Further information
- While the Winspit Quarry and caves are closed, people can still walk from Spyway, or the nearby village of Worth Matravers and down to the South West Coast Path which runs past the site
