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  The Mammals of Texas - Online Edition

Pallid Bat
Order Chiroptera : Family Vespertilionidae : Antrozous pallidus (Le Conte)

Pallid Bat (Antrozous pallidus).  Photo by Merlin D. Tuttle, Bat Conservation International.Description. A rather large, pale, yellowish-brown bat. Ears about 2.5 cm long, broad, naked, and crossed by nine or 11 transverse lines; bases of hairs light (nearly white), tips dusky; large light spot between shoulders; underparts paler and lacking dusky-tipped hairs; membranes nearly naked and brownish; nostrils surrounded by a glandular ridge producing a blunt snout; feet relatively large and strong. Dental formula: I 1/2, C 1/1, Pm 1/2, M 3/3 X 2 = 28. External measurements average: total length, 113 mm; tail, 46 mm; foot, 12 mm; ear, 28 mm; forearm, 48 mm. Weight, 12-17 g.

Species distribution mapDistribution in Texas. A common resident of the western one-half of Texas where two distinct races are known: A. p. bunkeri in the northern Panhandle and A. p. pallidus in the west and south.

Habits. Pallid bats inhabit rocky, outcrop areas where they commonly roost in rock crevices, caves, and mine tunnels but they also roost in the attics of houses, under the eaves of barns, behind signs, in hollow trees, and in abandoned adobe buildings. Colonies are usually small and may contain 12-100 bats. Pallid bats usually appear on the wing relatively late at night, well after dark. The species is probably migratory although occasional individuals have been reported from the United States in winter.

Their feeding habits are unlike those of most American bats. For years naturalists have noted the kitchen middens of discarded wings and other hard parts of insects under their "feeding roosts." Among them were remains of Jerusalem crickets, scorpions, and other flightless arthropods, although their diet also includes flying insects. To some extent though, pallid bats are terrestrial foragers. They have been observed flying, apparently at random, over an area at levels of 15-90 cm above the ground. When prey is located, presumably by sight, the bat abruptly drops to the ground, searches briefly, grabs its victim in its mouth, and takes off. Captured prey is taken to a feeding station where it is consumed. A. E. Borell described how one of these bats consumed a grasshopper. While eating, the bat hung head upward, supported by the thumbs, with the wings partly spread. The legs held the posterior part of the body well out from the timber and with the tail curved forward against it; the interfemoral membrane formed a pouch to catch parts of the large insect as they dropped.

Other than the items mentioned above, pallid bats also eat moths, froghoppers and leafhoppers, June beetles, and grasshoppers. In fact, 54 different types of prey have been documented for the pallid bat. Large, night-flying insects and ground-dwelling arthropods are most prevalent in the diet, however.

Mating occurs in fall with parturition in early summer. Females may carry one to four embryos but the birth of twins is usual. The length of gestation is 53-71 days. In Texas, the baby bats are born in early May to mid-June. Newborn bats weigh approximately 3 g and seem to develop more slowly than other species. The eyes open at 8-10 days of age, hair is evident at 10 days, and the young are volant by 6 weeks of age. Young bats have been found to contain both milk and insect remains in their stomachs, indicating that the young continue to nurse after becoming volant.

Photo credit: Merlin D. Tuttle, Bat Conservation International.

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