© John Kaczanow

The Brown 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. It is also common and widespread in the rest of Europe, except for southern Spain, southern Italy and Greece.

It has declined in Britain due to changing land use, including modern intensive agricultural practices, which have resulted in the loss of suitable feeding habitats and hollow trees for roosting. It is particularly susceptible to pesticides, especially their use in roofs where it often roosts on exposed timbers.

Flight & ultrasound

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 also known as 'whispering bats' because their echolocation sounds are very quiet. They have particularly sensitive hearing and often locate prey from just the sound made by the insect's own movements and not bothering to echolocate. 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 the wings of moths such as the Yellow Underwing.

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.

Brown Long-eared bats echolocation calls range from 25 to 50 kHz and are best heard around 50 kHz. 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.

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 3 weeks the young is fed solely on its mother's milk, and is left in a crèche inside the roost when the mother goes out to feed. Within 3 weeks the young make their first flights inside the roost and by 6 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 their roost. They do not normally leave until 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 1 to 2 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, for example 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.

In Great Britain, all bats are fully protected under Schedule 5 of the Wildlife and Countryside Act (1981) as amended, and by the Conservation (Natural Habitats etc) Regulations (1994). An agreement on the Conservation of Bats in Europe (EUROBATS) under the auspices of the Bonn Convention, also known as the Convention on Migratory Species (CMS) is in force, and all European bats are listed under Appendix II of the CMS .