A medium-sized bat, easily told apart from other species within the genus by its huge outer ears – fold it forward and it will protrude beyond the muzzle by about half its length. The auricles are fused on the forehead and have 22-24 lateral pleats; during hibernation, they are tucked away under the wings. Bechstein's Bat is found in mixed and deciduous forests, where it hunts, and where it lives inside hollow trees. It forms colonies of three to ten individuals. It usually hibernates in mining galleries or caves.