Macrotus californiens Baird, 1858, California, United States.
OTHER COMMON NAMES None known.
Head and body length 2.1-2.5 in (53-64 mm); tail 1.4-1.6 in (35-41 mm); forearm 1.9-2.1 in (48-54 mm); weight 0.4-0.7 oz (12-20 g); upper body is brown or gray, lower body is brown or buff with a silvery wash.
Southwestern United States and northwestern Mexico, including Baja California.
Arid subtropical lowlands; roosts in caves, mines, and abandoned buildings.
A relatively sedentary, nonmigratory species that is active year-round at its northern distributional limit, where it roosts in ge-
othermally heated mines in the winter; forms roosts of a few hundred to 1,000 or more individuals; occurs in many small, scattered colonies throughout its range.
Feeds on insects, including relatively large orthopterans and moths, which it captures in flight and by gleaning from vegetation and the ground; begins to forage well after sunset.
This species is monestrous and probably polygynous. Males and females form colonies in which mating takes place in September and October; males attract females with wing-flapping and vocal displays. Embryonic development is slow during the winter and faster in spring; gestation period is eight months. Females form maternity colonies, and babies are born in June.
Considered Vulnerable in the United States by the IUCN because of its small roost sizes.
SIGNIFICANCE TO HUMANS None known. ♦
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