Greater Mouse-eared

Greater Mouse-eared hangingThe Greater Mouse-eared bat (Myotis myotis) was supposed to have become extinct in Britain when a lone 17 year old male did not return to his hibernation site in Sussex in 1991. The last known colony was a few miles from Bognor Regis and contained several females until 1985 which was the year of their mysterious disappearance. Their departure happened 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 in this incident.

However an emaciated female was found (January 2001) in Bognor Regis but died shortly afterwards. It is thought that she may have been moving between hibernation sites and was caught out by the cold weather. From her worn teeth she was presumed to be quite old. She was found within 5 miles of the last known colony. The BCT hope to survey the area this summer to try and see if there are any more of this rare bat 'hanging on in there'.

It is a large bat and would be the largest British bat if it is still present. Its numbers declined in Europe during the 1970's but lately numbers appear to have stabilised.

Greater Mouse-eared in flight The Greater Mouse-eared Bat is primarily a cave dweller and suffers from extensive disturbance and loss of roosts. In most caves only a few bats may be found, but some caves are immensely important because thousands of bats from a wide area gather in them. Unfortunately the largest numbers of bats tend to be found in the largest caves, these are generally the most prone to disturbance through vandalism, caving, tourism and waste disposal.

The decline of this bat is also associated with the widespread use of agrochemicals, especially insecticides which can poison bats. The most important agricultural change to affect these bats is the loss of pasture and increase in area of improved grassland. This conversion significantly reduces the quantity and variety of food insects available.

  Greater Mouse-eared bat call on a Time Expansion bat detector.

Head and Body Length 67 - 80 mm
Forearm Length 54 - 68 mm
Wingspan 350 - 450 mm
Weight 28 - 40 g
Colour The dorsal fur is a sandy colour which contrasts strongly with the white fur underneath.
Life Cycle  
Mating Period August onwards.
Maternity Colonies From March to June
Colony Size 10 - 30 females.
Young: 1 born beginning of June.
Longevity 22 years.
UK Status Extinct?
Habitat and Food  
Summer Roosts Stone buildings, trees.
Winter Roosts Caves, tunnels, mines.
Feeding Habitat Woodland bat. Also found in parks, pasture and human settlement.
Food Ground beetles, cockchafers, dung beetles, grasshoppers, crickets, moths, spiders.
further reading

"Foraging Bats Avoid Noise"
Andrea Schaub, Joachim Ostwald, and Björn M. Siemers - Journal of Experimental Biology 211, 3174-3180 (2008)