[2] The Greater mouse-eared bat is relatively large for a member of the genus Myotis, weighing up to 45 grams (1.6 oz) and measuring 8 to 9 cm from head to tail (a little larger than a house mouse, Mus musculus), making it one of the largest European bats.

[4] The greater mouse-eared bat can be found throughout Europe, with populations in most European countries except Ireland, Denmark, Latvia, Estonia, Finland and the Scandinavian Peninsula.

However, the bats at the only known hibernation roost declined until only a few males were left, and when these disappeared the species was believed locally extinct.

[7] However, occasional individuals have been discovered in recent years, suggesting either that a colony survives or that further animals have colonized Great Britain from mainland Europe.

[6][8] In 2012, a LIFE-Nature project was initiated, aiming to protect the several thousands of greater mouse-eared bat in the Gola della Rossa and Frasassi Nature Park in the Marches.

[9][10] As a result, it uses echolocation only for spatial orientation, even if it emits ultrasound calls when approaching prey.