Daubenton's bat: Myotis daubentonii
Daubenton's bat is a medium-sized species. It has a steady flight, often within a few centimetres of the water surface and is reminiscent of a small hovercraft. Daubenton's bats take insects from close to the water surface. They have been seen taking prey directly from the water surface, using their large feet as a gaff or the tail membrane as a scoop. Daubenton's bats fly at about 25kph (15mph).
Daubenton Facts
| Description | |||
|---|---|---|---|
| Head and body length | 45 - 55mm | ||
| Forearm length | 34 - 41mm | ||
| Wingspan | 240 - 275mm | ||
| Weight | 7 - 12g | ||
| Colour | Furred brown, pale underneath. Pinkish face, bare around the eyes | ||
| Life cycle | |||
| Mating period | Autumn and throughout the winter | ||
| Maternity colonies | Established late spring. Young: one, born end of June to early July, weaned at six weeks | ||
| Colony size | 25 - 50 bats (up to 200) | ||
| Longevity | Up to 22 years | ||
| Habitat and food | |||
| Summer roosts | Tree; also tunnels, bridges, cave, mines, cellars; occasionally stone buildings | ||
| Winter roosts | Caves, mines and other underground sites | ||
| Feeding habitat | Over lakes, rivers and ponds | ||
| Typical food | |||
| Small flies | Midges | Caddis flies | Mayflies |
Daubenton's bats usually feed within about 6km of the roost, but have been recorded following canals for up to 10km. It is thought that they need to drink more frequently than some other species. Thus our old name of "water bat" is quite appropriate, but they often travel across land and occasionally feed away from water.
Breeding
Mating takes place in the autumn and active males will seek out females throughout the winter. Maternity colonies consist almost entirely of adult females. Maternity roosts are occupied from late spring sometimes until October. Young bats are suckled from several weeks and are fully weaned and able to forage for themselves at six to eight weeks. Males or non-breeding females mat aggregate during the summer to form their own communal roosts, but sometimes join maternity colonies.
Summer roosts
In England and Wales, the majority of known summer colonies are in humid, more or less underground sites near water. These may be tunnels or bridges over canals and rivers; or in caves, mines and cellars. They are only occasionally found in buildings, usually old stone buildings such as moated castles and waterworks. In Scotland, colonies more frequently occur in houses.
Tree holes are probably much more widely used than the recorded evidence suggests and one individual was even observed entering a small hole in an earthen roadside bank. They have also bred in bat boxes.
Summer colonies are often quite noisy throughout the day, especially at sites where they are close to human activity. A variety of temporary night roosts are used, often in trees or tunnels close to their feeding sites. Daubenton's bats have been found clustering with pipistrelles, noctule, Natterer's and brown long-eared bats.
Winter roosts
Many Daubenton's bats hibernate in caves, mines and other underground sites. In extensive tunnel systems with large numbers of bats present, Daubenton's are often the most numerous. They enter these winter sites in October, but only small numbers are present in the early part of winter.
Numbers can increase dramatically towards the end of January and in February, and individuals often remain at these sites until the end of March or even early April. Most are found in the warmer more stable environment within a site, although they can be found close to the entrance particularly later in winter.
Although usually solitary, small groups of three or four are not uncommon. Individuals are often lodged in tight crevices; many are barely visible and it is likely that others are not visible at all.
They may also hide amongst rocks and scree on the floor of caves and tunnels. Thus finding Daubenton's bats can be very difficult and it is likely that the numbers counted in many sites are a considerable under-estimate of the numbers actually present.
Ultra-sound
Daubenton's bat ultrasound calls range from 35-85 kHz and peak at 45 - 50 kHz. On a bat detector the calls are a machine-gun like series of regular clicks for bursts of 5 to 10 seconds.
Status and distribution
Daubenton's bat occurs throughout Europe, across to Korea and Japan. It is thought to be increasing in numbers in parts of Europe. In Britain it is fairly widespread up to northern Scotland, in Ireland and the Isle of Man.
Conservation
Despite severe loss of and damage to wetlands and waterways, Daubenton's bat seems to be increasing in parts of its range. This may, in part, be associated with increasing numbers of artificial water bodies, including gravel pits, reservoirs and flooded quarries. Also a low level of pollution may encourage a more consistent supply of chironomid midges. However, the loss of diversity of aquatic insects has a detrimental effect on other animals and without very careful pollution controls would also affect Daubenton's bat. The removal of waterside trees and disturbance to hibernation sites could also lead to a decline in this species.
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