Llanelli Naturalists Newsletter - Summer 1992
A.M. Hutson & S. Mickleburgh

Brown Long-eared Bat Plecotus auritus

Long-eared bats have a head and body length of up to 50mm (2") and a wingspan of about 250mm (10"), a medium sized bat by British standards. Their fur is usually light brown on the back and pale underneath. They weigh only about 8-10g (about ½oz) The ears are nearly as long as the body, but are not always obvious; when at rest long-eared bats may curl their ears back like ram's horns, or tuck them away completely under their wings leaving only the pointed Inner lobe of the ear Wag us) visible.

Long-eared bats are gleaners, often flying slowly amongst foliage picking insects off leaves and bark. Sometimes they land on the ground to catch insects or to shift them into a controlable position in the mouth. Their broad wings and tail allow slow, highly manoeuvrable hovering flight and even allow them to take insects from lighted windows. Their flight often includes steep dives and short glides. Their echolocation sounds, which are emitted through the nose, are very quiet and as a consequence they are known as "whispering bats". There are two possible reasons for these quiet sounds; since they feed amongst foliage, producing loud sounds could result in confusing or deafening echoes, or, as some insects can detect ultrasound, producing quiet sounds could enable a long-eared bat to surprise its prey. The large ears may assist in picking up faint echoes. They feed mainly on moths, although they will also take certain flies, beetles, bugs, earwigs and spiders. Small prey Items are eaten in flight, but larger prey Is taken to a so-called "perch". These perches, which are frequently inside porches and barns, are Indicated by the piles of discarded insect remains, particularly the wings of moths such as the yellow underwing, beneath them. The favoured feeding habitats of long-eared bats are open deciduous woodland and old parkland.

Their habit of flying close to the ground or even landing to tackle prey items makes them vulnerable to attack by predators and many of the bats falling victim to domestic cats are long-eared bats.

Breeding

Long-eared bats often move into their breeding roosts earlier than other species; these roosts can be occupied as early as April and may be used until October or sometimes for the entire year. The numbers visible in maternity roosts are usually small, frequently fewer than 20, although roosts of 50 or more are known and often only part of the colony Is visible. Mating normally takes place in the autumn, though it can occur In the winter or even spring and the female usually gives birth to its single young in late June to mid-July. For the first three weeks of life the young feed only on their mother's milk, and are left in a crèche inside the roost when their mothers go out to feed. Within three weeks the young make their first flights inside the roost and within six weeks they are fully weaned and able to forage for themselves. Most females breed in their first year but do not necessarily breed every year. 

Males are sexually mature in their first summer. Females have been known to live for 17 years, while the record for males Is only 10 years.

Roosts

Summer

Many roosts have been found in buildings, particularly older ones with large open roof spaces, where bats roost singly or in small groups around ridge ends, pitch junctions, around chim-neys and in crevices in ridge tiles. Long-eared bats are more frequently visible inside the roof space than many other bats. The most obvious type of group is the maternity group. This consists mainly of breeding females though, unlike other species, a significant proportion of males may also be present. Long-eareds may leave their roost from a variety of places and small amounts of droppings may be evident wound these points. Within the roost there may be small accumulations of droppings beneath favoured roost sites, and a sparse scattering of droppings generally over the floor of the roof space.

Long-eared bats are generally very quiet inside their roost. They do not normally leave their roost until well after dark, although they are active, stretching, grooming and flying inside the roost, for up to an hour before emergence. When they have young to feed, females return to the roost after one to two nours to suckle them, but at other times bats may remain away from the roost until dawn. The small size of roosts and their frequency might suggest that long-eared bats have a small feeding range. Long-eared bats will also roost in tree-holes or bat boxes — 65 have been found in one box!

Winter

A variety of sites are used. Only a tiny proportion of long-eared bats seen in summer are found in winter, probably because most spend winter in trees or tucked away in buildings, for example in hollow walls, where their presence is not obvious. Small numbers are found in underground sites such as caves, tunnels, mines and ice-houses, particularly after prolonged cold spells. In these sites, they sometimes hang in the open, on the walls or from the ceiling although they also roost in crevices. Long-eared bats prefer to hibernate at low temperatures and have been known to tolerate temperatures down to 0°C.

Further Reading

Corbel. G. B. 8. Southern, H. N. 1977. Tio Holdhook ol British Mammals. Mammal Society/Blackwell Scientific Publications. Oxford, 520pp, £15.00. (3rd Edition expected 19891. Hutson, A. M. 1987. Bats in Houses. Fauna and Flora Preservation Society, London, 32pp, £0.60

Richardson. P. W. 1985. Bats. Whittet Books. London, 128pp £5.95

Schober, W. 1984. Till 1.1ril if Bats. 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 roost, the Nature Conservancy Council must be consulted. Local bat groups will also be happy to give help or advice.