Bats are known to move to hibernation sites in autumn
DURING OCTOBER, ONE OF BRITAIN AND Ireland’s least-familiar wildlife spectacles is underway, witnessed by a handful of the most ardent nature enthusiasts. It occurs only after dark, but not even every night, and if you go, chances are you won’t be able to see anything.
This is the autumn bat swarming season, best enjoyed with a bat detector. After breeding in summer, many bats abandon their maternity roosts and leave the breeding area, travelling to hibernation sites that may be some distance away.
Species that hibernate underground have very particular needs, favouring caves, old mines and tunnels used by generations of bats. Among them are long-eared bats and several species in the genus Myotis, including Daubenton’s, Natterer’s, Brandt’s and whiskered bats.
At the entrance to these special places, bats from different colonies get the opportunity to mingle. These swarms are where mating takes place, with females storing the sperm throughout the coming winter as they hibernate, until restarting their pregancy in spring.
Ben Hoare