Llanelli Naturalists Newsletter - Winter 1994/1995
A.M. Hutson & S. Mickleburgh

Daubenton's bat Myotis daubentonii

Daubenton's bat is one of our medium-sized species with a head and body length of 45mm (13/4-), a wingspan of 250mm 1 0) and a weight of about 9g (1/3oz). The fur is short, red-brown on the back and pale underneath. It has a pinkish face and Quite short, rounded ears.

Daubenton's bats emerge after it has become quite dark, but are frequently easy to see feeding over lakes, rivers and even quite small ponds. The steady flight, often within a few centimetres of the water surface, is reminiscent of a small hovercraft Their food is largely caddisflies, mayflies. various small flies and other insects taken from or just above the water surface. They have been observed taking food from the surface of the water, often using their large feet as gaffs or their tail membrane as a scoop. They usually feed

 

 

within about 6km of the roost but have been recorded following canals for up to 10km. It is thought that Daubenton's bats need to drink more frequently than other species. Thus. their old name of "water bat" is quite appropriate, but they often travel across land and occasionally feed away from water.

Breeding

Maternity colonies consist mainly of adult females and usually number between 40 and 80 bats. although they have been known to exceed 100 individuals. The single young is born at the end of June or early July. Young bats are suckled for several weeks and are fully weaned and able to forage for themselves at six to eight weeks, but the colonies often remain together until October. Males may aggregate during summer to form their own communal roasts and sometimes join female colonies in summer. Most mating takes place in the autumn, but active males will seek out females at any time of the winter.

Daubenton's bats have been known to live for over 22 years.

Roosts

Summer

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. Occasionally they are found in buildings, usually old stone buildings

such as moated castles and waterworks. In Scotland, colonies are more frequently found 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 earthern roadside bank. 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 other bats, such as pipistrelles, Natterer's. brown long-eared bats and noctules.

Winter

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 the winter. Numbers can increase dramatically towards the end of January and February and individuals often remain at these sites until the end of March or even early April. They are usually found in the warmer more stable environment within the site, although they can be found close to the entrance, particularly later in the 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 among 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 an underestimate of the numbers actually present.

Further Reading

Corbel G.B. & Southern H.N. 1977. The Handbook of British Mammals. Mammal Society/Blackwell Scientific Publications.

Oxford, 520pp. £15.00 (3rd Edition expected 1988) Hutson, AM. In press. Bats ln Houses Fauna and Flora

Preservation Society. London, (expected 1987). Richardson. P. W. 1985. Bats. whiffet Books. London 128pp. £5.95 Schober, W. 1984. The Lives of Bits, Croom Helm, Kent. 200pp. £ 13.95.

Stebbings, R.E. 1986. Bats. Anthony Nelson. Shropshire (Mammal Society Series). 32pp. £2.50.

Bats and the law

Bats and their roosts are protected under the Wildlife and Countryside Act 1981. Should any work be planned that may disturb bats or their roosts. the Nature Conservancy Council must be consulted. Local bat groups will also be happy to give help and advice.