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Cabeza Prieta Natural History Association
Sonoran Desert Mammals

Coffee Pot Mountain


Underwood's mastiff bat
(Eumops underwoodi)

 Underwood's mastiff bat

Diet: grasshoppers, leafhoppers, moths, and beetles
Size: weight 50-60 grams (1.8-2.1 ounces) wingspan 50-55 centimeters (20-22 inches)
Active Period: nocturnal
Abundance: rare

Among bats of the United States, this species is second in size only to the greater mastiff bat. The range within the United States is limited to the vicinity of the Baboquivari Mountains and the Organ Pipe Cactus National Monument, but occurs along the western coast of Mexico into Central America.

The flight speed is at least 43 kilometers (26 miles) per hour. As in other free-tailed bats, the distal part of the tail is not attached to the interfemoral membrane.

Information on habitat of this species in the U.S. is scarce and its distribution in winter is unknown.

Roosts are in high dry places; one roost was in a large, hollow tree. Its presence can be detected by listening for the high-pitched "peeps" emitted several times a minute in flight. The calls may be intense enough to hurt the ears of anyone standing close by when these bats are flying.

One baby is born in late June or July. Underwood's mastiff bat is rare in the United States and is of special concern.

This article is from "Bats of the United States", 1999, by Michael J. Harvey of Tennessee Technological University, J. Scott Altenbach of the University of New Mexico, and Troy L. Best of Auburn University. Published by the Arkansas Game & Fish Commission, in cooperation with the Asheville Field Office of the U.S. Fish and Wildlife Service.

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Natural History of the Sonoran Desert and Refuge