Brown long-eared bat: Plecotus auritus
Long-eared bats are medium sized. The ears are nearly as long as the body, but are not always obvious: when at rest long-eared bats curl their ears back like rams' horns, or tuck them away completely under their wings leaving only the pointed inner lobe of the ear (tragus) visible. The brown long-eared bat is very difficult to distinguish from the very rare grey long-eared bat (P. austriacus) of southern England.
| Description | ||||
|---|---|---|---|---|
| Head and body length | 37 - 48mm | |||
| Forearm length | 34 - 42mm | |||
| Wingspan | 230 - 285mm | |||
| Weight | 6 - 12g | |||
| Colour | Adults light brown, pale underneath; juveniles greyish | |||
| Life cycle | ||||
| Mating period | October to April | |||
| Maternity colonies | Established late spring. Young: one born late June to mid-July, weaned at six weeks | |||
| Colony size | 10 - 20 (occasionally more than 50) | |||
| Longevity | Up to 30 years | |||
| Habitat and food | ||||
| Summer roosts | Older buildings, barns, churches & trees | |||
| Winter roosts | caves, tunnels, mines, ice-houses; probably trees & buildings | |||
| Feeding habitat | Open deciduous & coniferous woodland, parkland, orchards | |||
| Typical food | ||||
| Moths | Dung beetles | Flies | Earwigs | Spiders |
As well as catching insects in free flight, long-eared bats are gleaners, often flying slowly amongst foliage picking insects off leaves and bark. Their broad wings and tail allow slow, highly manoeuvrable hovering flight. Sometimes they land on the ground to catch insects or to shift them into a controllable position in the mouth and are even able to take insects from lighted windows. Their flight often includes steep dives and short glides.
These bats are known as "whispering bats" because their echolocation sounds are very quiet. They have particularly sensitive hearing and often locate prey from the sounds made by the insects own movement. They may also sometimes use vision. Small prey is eaten in flight, but larger insects are taken to a "perch". Regularly used perches, which are frequently inside porches or barns, can be recognised by the accumulations of discarded insect remains, particularly wings of moths such as yellow underwings.
Their habit of flying close to the ground, or even landing to tackle prey, makes them vulnerable to attack by predators and many long-eared bats fall victim to domestic cats.
Breeding
Maternity roosts may be occupied from early April through to October or later, and are occasionally used for the entire year. Unlike other species a significant proportion of males may be present in maternity roosts.
The female usually gives birth to its single young in late June to mid-July. For three weeks the young is fed solely on its mothers milk, and is left in a creche inside the roost when the mother goes out to feed. Within three weeks the young make their first flights inside the roost and by six weeks are fully weaned and able to forage for themselves. The numbers seen in maternity roosts are usually small, although often only part of the colony is visible.
Most females breed in their first year, but do not necessarily breed every year. Males are sexually mature at about 15 months old.
Summer roosts
Many roosts have been found in buildings, particularly older ones with large open roof spaces. Bats roost singly or in small groups among the roof timbers of the apex, especially around ridge ends and chimneys, and in crevices in ridge tiles. The favourite roost sites are often indicated by grease marks on the timbers.
Long-eared bats spend more time inside the roof space than many other bats. They may leave their roost from a variety of places and small amounts of droppings may be evident around these points. Within the roost there are small accumulations of droppings beneath favoured roost sites, and a sparse scattering of droppings generally over the floor of the roof space, particularly below the ridge. They will also roost in tree-holes and bat boxes - 65 were once found in one box.
Long-eared bats are generally very quiet inside the roost. They do not normally leave until 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 hours to suckle them, but at other times may remain away until dawn. The small size of maternity colonies and their frequency might suggest that long-eared bats have a small feeding range.
Winter roosts
Hibernation begins in November and a variety of sites are used. Only a tiny proportion of the long-eared bats seen in summer are found in winter, probably because most spend the winter in trees or tucked away in buildings in hollow walls, where their presence is not obvious. Small numbers are found in caves, tunnels, mines and ice-houses, particularly early in the winter and 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 very cold temperatures, often just above freezing.
Ultra-sound
Brown long-eared bats echolocation calls range from 25 - 50kHz. On a bat detector the calls are very quiet and are heard as a series of clicks rather like those produced by a Geiger counter.
Status and distribution
The long-eared bat is the second most common species in Britain and is found throughout the UK, Ireland and the Isle of Man. It is absent from Orkney and Shetland and other exposed islands. Its is also common and widespread in the rest of Europe, except for southern Spain, southern Italy and Greece.
Conservation
The long-eared bat has declined in Britain due to changing land use, including modern agricultural practices, which have resulted in the loss of suitable feeding habitats and hollow trees for roosting. It is particularly susceptible to pesticides, including in roofs where it often roost on exposed timbers.
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