Brown long-eared bat

GB: Least concern

England: Least concern

Scotland: Least concern

Wales: Least concern

Global: Least concern

Head & body length: 37mm - 52mm

Forearm length: 34mm - 42mm

Wingspan: 230mm - 285mm

Weight: 6g - 12g

Thumb: More than 6.2mm (in comparison with grey long-eared bat)

Tragus: Greatest width less than 5.5m (in comparison with grey long-eared bat)

Colour: Adults have light brown fur, pale underneath; juveniles greyish - beware confusion with grey long-eared bat!

As well as catching insects in free flight, brown 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 they are even able to take insects from lighted windows. Their flight often includes steep dives and short glides.

Brown long-eared bats are known as ‘whispering bats’ because their echolocation sounds are very quiet. They have particularly sensitive low frequency hearing and often locate prey from the sounds made by the insect’s own movements. They may 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 brown long-eared bats vulnerable to attack by predators.

Summer roosts of brown long-eared bats are usually located in older buildings, barns, churches and trees. Long-eared bats generally form small and quiet colonies of about 20 animals. Often, the first a householder knows about them is when a visit to the loft reveals a cluster of tiny faces peering down from a corner of the rafters!

Winter roosts tend to be found in caves, tunnels, mines, ice houses and occasionally even trees and buildings. Their foraging habitat is open deciduous and coniferous woodland, parkland and orchards.

Unlike the males of other species, a significant proportion of male brown long-eared bats may be present in the maternity roosts. Brown long-eared bats prefer to hibernate at very cold temperatures, often just above freezing point.

Brown long-eared bats mate in the autumn and active males will continue to seek out and mate with females throughout the winter.

Matenity colonies are established in late spring, with one young born around late June to mid-July, and then weaned at 6 weeks.

Colony size is between 10 to 20 bats (up to 50), and each brown long-eared bat can live for up to 30 years.

Brown long-eared bats’ echolocation calls range from 25 - 50kHz and peak at 35kHz.

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

The brown long-eared bat 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, and the conversion of barns which have resulted in the loss of suitable feeding and roosting habitats.

Brown long-eared bat is particularly susceptible to pesticides, especially their use in roofs where it often roosts on exposed timbers.