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Western Mastiff Bat Eumops perotis


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Western Mastiff Bat
credit: M. Siders

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Family: Molossidae, Free-tailed Bats view all from this family

Description The largest bat in North America is darker than Underwood’s Bonneted Bat, and lacks long guard hairs on the rump. Forearm 72-83mm. Males have a well-developed throat gland that emits a thick, smelly musk in the breeding season.

Dimensions 159-187mm, 55-72mm, 45-73g

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.

Habitat Canyons & caves

Range Southwest, Texas, California

Discussion Also known as the western bonneted bat, the greater mastiff bat, or the greater bonneted bat, roosts in cliffside crevices in rugged canyonlands of the arid southwest.