Greater mouse-eared bat

The greater mouse-eared bat is much larger than any other bat in the UK. It is also the rarest bat in Britain, and is no longer officially counted as a resident species as no maternity sites have been found for many years.

There are only two individuals let of this species in the UK.

The scientific name of the greater mouse-eared bat is Myotis myotis.

Greater mouse-eared bat IUCN classification

GB: Critically endangered

England: Critically endangered

Scotland: NA

Wales: NA

Global: Least concern

Vital Statistics

Head & body length: 65mm-80mm

Forearm length: 57mm-68mm

Wingspan: 365mm-450mm

Weight: 24g-40g

Colour: Its fur is a sandy colour, and it has a bare pink face with large ears that have a prominent tragus. The paler fur on its underside can be seen when they fly, which often follows a straight path along woodland edges or hedgerows.

General information

Greater mouse-eared bat

(c) John Black

The last hibernating population of greater mouse-eared bat contained around 30 bats. It was discovered in west Sussex in 1969 and it contained several females. However, in 1985 these disappeared around the time that a nearby cottage was destroyed by fire, and as the females tend to form maternity colonies in attics they may have perished then.

A single male was recorded hibernating in underground tunnels near Dover in 1987, but subsequent searches suggested this was a stray migrant. Numbers in the Sussex colony gradually declined to a lone 17 year-old male in 1990. However, in January 2001 an emaciated female was found within five miles of the last known colony, but she died shortly afterwards; from her worn teeth she was presumed to be quite old.

Then in December 2002 a male, considered to have probably been born that year, was found and ringed in the west Sussex hibernation site used previously by the species. It was present at the same site in the following January and February 2003, and has been observed there every winter since.

It was thought to be the only one in the UK, until January 2023, when a second bat was discovered in yet another tunnel. It is thought that these species may be crossing the channel from France to hibernate here. You can read more about the discovery of the second greater mouse-eared bat here.

Efforts have been made to identify likely summer roost and foraging sites, but there have been no other winter or summer records.

Greater mouse-eared bat habitat

In mainland Europe, greater mouse-eared bat maternity colonies usually dwell in large roof spaces, sometimes in huge numbers. In the Mediterranean area, caves are mostly used as maternity sites. Here, it hunts in open lightly wooded country, along woodland edges, over pasture and adjoining cultivated areas.

Interchange between adjacent nursery colonies seems frequent. Males are solitary or in small groups. In autumn males usually lure one to five females to a roost site in tree holes, bridges or buildings for mating.

The greater mouse-eared bats' flight is slow, heavy and generally straight. They forage very low, capturing most of their food on the ground.


Unfortunately we don't know about the foraging ecology of greater mouse-eared bat in the UK. However, elsewhere in Europe their diet consists of large beetles, caterpillars, maybugs, and crickets.

Reproduction and life cycle

No breeding sites identified in UK. Elsewhere in Europe, greater mouse-eared bats' maternity roosts are comprised of hundreds of individuals in roof spaces and caves.

The single young is born in the summer and starts to practice flying at 3-4 weeks of age. In Germany, 95% of the females between four and 14 years of age are involved in reproduction; older animals no longer give birth annually.

Echolocation of greater mouse-eared bat

Sounds produced by greater mouse-eared bats are above the range of human hearing. With a bat detector (heterodyne) the echolocation calls can be picked up at about 34 kHz, although this can vary.

Distribution and conservation

The greater mouse-eared bat is classified as critically endangered in England and Great Britain. Because of the limited distribution of records, a range map cannot be calculated. However, it is possible there are undiscovered summer roosts - of either maternity colonies or solitary males - in southern England.

The greater mouse-eared bat hasn't been declared extinct due to a lack of exhaustive searching.