External characteristics: As indicated by its name, the Townsend's big-eared bat has big ears, which are about one half the length of its body. Its tragus is long and pointed. This bat also has broad wings and a short snout with two glandular masses on either side of its muzzle. Its fur is long and varies from pale brown to blackish-grey. Its fur is darker at the root than it is at the tips. Females can be slightly larger than males. It is also known as the Western long/big-eared bat, the Western lump-nosed bat or the Mule-eared bat.
Habitat: The Townsend's big-eared bat mostly inhabits the West of North America. This species is found in a variety of habitats from coastal forests to arid grasslands. The Townsend's big-eared bat uses caves, old mines and buildings as summer roosts. Females form colonies of a dozen up to several hundred individuals, while males roost alone. As winter approaches, individuals begin to migrate to caves or mines for hibernation. The distance between the summer roost and the winter hibernaculum is usually short (around 10 to 65 km).
Reproduction: Mating takes place in late autumn or early winter, usually at the winter roost. Females give birth to a single pup after a pregnancy of 50 to 100 days, depending on ambient temperatures and the length of time that the female spends in torpor during gestation. The young are born in June or early July. Weighing at around 2.4 grams, the young mature quickly and reach their adult size after approximately 4 weeks.