Family: Vespertilionidae, Vespertilionid Bats view all from this family

Description A large bat. Creamy to beige above; nearly white below. Big ears, separated at base. Wings and interfemoral membrane essentially naked. L 4 1/4–5 1/8" (107–130 mm); T 1 3/8"–1 7/8" (35–49 mm); HF 3/8"–5/8" (11–16 mm); FA 1 7/8–2 3/8" (48–60 mm); E 1–1 3/8" (25–35 mm); Wt 1–1 1/4 oz (28–37 g).

Warning Bats are susceptible to rabies, a serious viral disease that results in death if untreated. Rabid bats rarely attack humans or other animals, but bats found lying on the ground may be rabid. Never touch or pick up any bat. Stay away from any animal that seems to be acting strangely and report it to animal-control officers. If you are bitten by a possibly rabid animal, you must immediately consult a doctor for a series of injections; there is no cure once symptoms emerge.

Similar Species All other big-eared bats are darker.

Breeding Mates on horizontal surfaces or while hanging upside down in fall and perhaps in winter. Maternity colonies form in rock crevices, in buildings, and in other man-made structures. 1 or 2 young born usually May–June. Female is upright while giving birth, and young are caught in the flight membrane as they emerge.

Habitat Deserts and canyons. Daytime roosts in buildings and crevices; less often in caves, mines, hollow trees, and other shelters. Nighttime roosts in buildings, caves, mines, and cliff overhangs.

Range South-central British Columbia and ec Washington east to s Colorado, and south to s California and sw Texas.

Discussion Emerging long after dusk and beating its wings more slowly than many bats (only 10 or 11 beats per second), this stately bat is unusual in that it often feeds on the ground; several have been caught in mousetraps. Its food consists of many large insects, including flightless beetles, crickets, scorpions, and grasshoppers; in captivity, it has captured and consumed lizards. Its several calls include an insect-like buzz; high-pitched dry, rasping, thin double notes; single, clear, resonant high-pitched notes; and clicks. The first two generally are given when the colony is disturbed, the latter two at night in flight. The summer colonies, consisting of from 30 to 100 bats, are unusual in that they include members of both sexes and young. Night roosts, often near day roosts but distinct from them, are commonly used by this species. A skunk-like odor given off by glands on the muzzle is most pronounced when the bat is disturbed. Pallid Bats are presumed to hibernate, but few have been found in winter.
Sign: Droppings (guano) on hay in barns or on floors of buildings; they somewhat resemble mouse droppings, but are segmented and consist chiefly of insect fragments.