Daubenton’s Bat

Myotis daubentonii

Description and identification

A smallish bat with quite short ears, the Daubenton’s bat is also known as the ‘water bat’ as it feeds almost exclusively over water. Often seen just inches above the surface of calm ponds, lakes and rivers, it has a distinctive pale belly. Its fur appears reddish brown, but its face is pink and bare around the eyes. They have very large feet which they use to scoop up their insect prey.

Daubenton’s bat produces the characteristically short echolocation calls produced by all the Myotis bats. On a heterodyne detector they sound like a rapid series of dry clicks, almost the sound of burning stubble. Recordings of calls made by time expansion detectors often show the calls to be more S-shaped rather than the straighter calls produced by other Myotis bats. The frequency range typically goes from 85-35 kHz and calls are loudest between 40 and 50 kHz31.

Status and distribution

Present across all of Great Britain and Ireland, the Daubenton’s bat is expanding its range across the UK, possibly due to the creation of artificial waterways and lakes. In Nottinghamshire one has been recorded hunting over a roadside run-off pond!

The Daubenton’s bat is monitored across the UK as part of the National Bat Monitoring Programme’s ‘Waterway Survey’ and ‘Hibernation Survey’. The Hibernation Survey has shown a marked increase in the national population between 2013 and 2016; however this was not reflected in the Waterway Survey over the same time period. The Bat Conservation Trust considers the population to be stable since 199932, the baseline year for monitoring.

In Nottinghamshire it has a widespread yet scattered distribution. The majority of records are of bats in their foraging areas and only a few roosts are known.

Roosts

In summer Daubenton’s bats use a variety of places for their maternity roosts including holes in trees, buildings and bridges. In Nottinghamshire only five roosts have been discovered; one in a tree, two in buildings, one in a bridge and one in a rock crevice, although the species has been recorded throughout the county.

Winter, or hibernation roosts of Daubenton’s bat are generally in underground sites, old mines, tunnels, ice houses or caves. Due to the lack of suitable underground caves and mines in Nottinghamshire, it is likely that many Daubenton’s that remain in the county hibernate in manmade structures and trees and remain undetected.

Food and foraging

Daubenton’s bats catch insects which are close to, or on the water’s surface with their large feet, or by scooping up prey with their tail membrane. Daubenton’s bats primarily feed on aquatic midges, mayflies and caddis flies. Whilst they usually rely on waterways to feed, they are also associated with woodland, and sometimes solitary bats can be found foraging in this habitat.

The Daubenton’s bat is not as fast as some of the other UK bats, flying at approximately 25km/h and most bats will hunt within 6-10km from their roost.

Echolocation Calls
Daubenton's bats produce the characteristically short calls produced by all the Myotis bats. On a heterodyne detector they sound like a rapid series of dry clicks. They produce a fast series of calls which speeds up when the bat turns. Recordings of calls made by time expansion often shows the calls to be bent rather than the straight calls produced by other Myotis bats.

Time expansion (10x) recording of a Daubenton's bat.

Heterodyne (set at 45kHz) recording of a Daubenton's bat.


daubenton's bat time expansion call