One of our larger bats, the Big Brown Bat has a large, broad head, broad nose and long, lax fur. Its fur colour varies from pale to dark brown; the fur tends to be oily in texture. Its flight membranes and ears are black. The ears just reach the nose when pushed forward; the tragus is short and blunt. The calcar has a prominent keel. The skull is robust, with thick, heavy jaws, a flattened brain-case and large teeth.
IdentificationAlthough the Big Brown Bat resembles several of our Myotis species in colour, it can be readily distinguished by its large size (forearm greater than 42 mm), large head and long fur. The combination of 2/3 incisors and 1/2 premolars is unique among British Columbian bats.
Dental Formulaincisors: 2/3
Measurementstotal length: 116 (98-131) n = 126
tail vertebrae: 46 (37-55) n = 123
hind foot: 12 (8-15) n = 115
ear: 15 (11-21) n = 53
tragus: 8 (5-11) n = 40
forearm: 47.5 (43.0-52.0) n = 109
wingspan: 328 (205-393) n = 62
weight: 15.2 (8.8-21.9) n = 36