The Hoary Bat is the largest bat in British Columbia. It has a distinctive hoary colour. The long, soft fur on its back is a mix of dark brown and grey hairs that are tinged with white. There are small patches of yellow or white on its shoulders and wrists. Yellow fur also appears on the throat, around the ears and on the underside of the wing membranes. The wing membranes are dark brown with paler areas on the forearm and fingers. The ears are round and short with a short, broad tragus. The outer edge of the ear is black; yellow hairs are scattered on the inside of the ear. The dorsal surface of the tail membrane is densely furred; the hind foot is relatively small with a heavy covering of fur on the upper surface. The calcar has a narrow keel. The skull has a short, broad rostrum, large molars and a high profile.
IdentificationThe large size and marked colour pattern make the Hoary Bat one of our most distinct bats. The only species with remotely similar markings is the Silver-haired Bat (Lasionycteris noctivagans)-see that account for diagnostic external features. Among British Columbian bats, only the Western Red Bat (Lasiurus blossevillii) has a similar dental formula; the skull of the Hoary Bat can be discriminated by its greater size (skull length greater than 15 mm).
Dental Formulaincisors: 1/3
The tiny first upper premolar is usually hidden between the canine and second upper premolar.
Measurementstotal length: 137 (125-144) n = 11
tail vertebrae: 60 (50-66) n = 10
hind foot: 12 (10-15) n = 12
ear: 14 (13-16) n = 4
tragus: 9 (9-10) n = 4
forearm: 54.5 (50.3-57.4) n = 24
wingspan: 392 (338-415) n = 7
weight: 28.4 (20.1-37.9) n = 43