Bats in New Mexico

Greater Mastiff Bat GREATER MASTIFF BAT - Eumops perotis

Weight: 60-70 grams

Wingspan: 53-57 centimeters

Distribution: Central California to central Mexico and South America to northern Argentina.

Ecology and Behavior: Capable of fast and prolonged flight; the wings are long and slender and the flight membranes are tough and leathery. These bats live in high, dry places, and usually cannot get airborne from the ground, but will scramble to a post or a tree to gain height for launching. In the southwestern United States, the greater mastiff bat is most common in rugged rocky canyons and cliffs, where crevices provide favored daytime retreats. Colonies are small, usually less than 100 individuals, and adult males sometimes are found in maternity colonies. Some roost sites are occupied throughout the year, but the four seasons usually are spent in different roosts. This species produces a high-pitched call that can be heard when individuals are flying up to 300 meters (990 feet) above ground. Males have a dermal gland that can become enlarged during the mating season. When enlarged, this gland produces a thick, oily secretion with a strong odor that may serve to attract females.

Food Habits: Feeds on insects, including dragon flies, grasshoppers, beetles, true bugs, moths, wasps and ants.

Reproduction: Mating occurs in early spring when the dermal gland of the male is most functional. Parturition dates vary more in this species than in any other bat in the United States, May to September. One baby ordinarily is born, twins are rare.

Status of Populations: Locally common.

Thanks to T. L. Best, J. S. Altenbach, and M. J. Harvey for permission to reprint portions of Bats of the Western United States, 1998.

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