Echolocation
Calls range from 35 to 85 kHz, heard on a bat detector as a machine-gun-like series of rapid regular clicks. This can be heard more clearly if the detector is set at 35 kHz, so as to cut out most of the pipistrelle calls.
Habits
Radio-tracking has shown that they will typically forage within three kilometres of the roost, but may fly 15 km or more along the river in a night’s activity, feeding over calm water. Although usually associated with water they will also forage in nearby woodland along paths and tree lines, but rarely very close to vegetation clutter.
Reproduction and life cycle
The few known summer roosts are close to the water, in tree holes or bridges, but very few are found compared with the number of bats seen flying. Bats roosting in trees move between roosts more often than those in bridges. Stone buildings such as churches or castles are occasionally used in England, though more often in Scotland.
Swarming occurs in late summer and early autumn around hibernation sites. Many hibernate in caves, mines and other underground places with cool humid conditions, both in crevices and in the open. Mating takes place in the autumn and throughout hibernation.
Distribution, status and conservation
Daubenton’s bat is widespread in the UK, and seems to be increasing in parts of its range. This may in part be due to the low level of pollution common along our waterways, as it supports their preferred aquatic insect prey. Official NBMP data (2024) show stable long-term trends, with some emerging short-term concerns.
Although very few summer roosts have been located in Kent, these bats may be seen flying over the majority of our rivers, lakes and ponds. It is one of the two species found most frequently in winter, hibernating in cool humid underground sites, including tunnels, chalk mines and deneholes.
