DAUBENTON’S BAT Myotis daubentonii

 

Status: Native; Fairly Common

 

Habitats:  River/Lake; Woodland

 

This is a medium-sized bat, with a body length of 5 cm, and a wingspan of around 28 cm.  The fur is bronze / brown on the dorsal (upper) surface, and grey / buff on the ventral (lower) surface.  The bat has large feet and a bald, pinkish patch around each eye; the ears are relatively small.

 

Daubenton’s bats are strongly associated with water, leading to their alternative name of Water Bat.  They prefer feeding low over calm and sheltered lakes and wide rivers, skimming insects from the water’s surface (their large feet are adapted to gaffing / trawling prey from the surface of the water).  They seldom fly more than a metre above the water, and tend to fly in straight, direct lines.

 

They may also hunt in other habitats, including along the edge of woodland.

 

Radio-tracking surveys in the Yorkshire Dales have shown that individual Daubenton’s bats tend to feed in the same location night after night; only two or three regular feeding areas are typically used by each bat, and each may measure between 30 and 100 metres in length.  Fascinatingly, this species has been found to exhibit gender separation at foraging areas; females normally feeding without the competition of males in lower (and more insect-rich) parts of river catchments.  This is thought to help ensure that the females eat enough insects to provide their young with sufficient milk, whilst reducing the amount of energy the female needs to expend to catch the insects.

 

The Daubenton’s bat is found throughout England, Wales and most of Scotland, the estimated British population being 150,000.

 

Daubenton’s bats roost in a variety of places, including trees, but they are most commonly found in stone bridges over rivers and close to lakes.  They normally feed within 3 km or so of their roost, although they have been recorded flying over 15 km to feeding sites on occasion.

 

As with the Natterer’s bat, Daubenton’s bats ‘swarm’ in large numbers in the autumn.  This involves the gathering of large numbers of bats around particular tunnels and cave systems in order for them to mate and socialise.  The complete function of swarming activity is not fully understood, but the places in which they gather have been compared to a disco or night club !