Bats in New Mexico

Big Brown Bat BIG BROWN BAT - Eptesicus fuscus

Weight: 14-21 grams

Wingspan: 32-39 centimeters

Distribution: Southern Canada through southern North America into South America, including many islands in the Caribbean.

Ecology and Behavior: These bats are closely associated with humans and are familiar to more people in the United States than is any other species of bat. Most summer roosts are located in attics, barns, bridges or other man-made structures, where colonies of a few to several hundred individuals gather to form maternity colonies. They move into caves, mines and other underground structures to hibernate only during the coldest weather. Where most of these bats winter remains unknown. This species emerges at dusk and flies a stead, nearly straight course at a height of 6-10 meters (20-33 feet) in route to foraging areas. Its large size and steady flight make it readily recognizable. Apparently, some individuals use the same feeding ground each night, for a bat can sometimes be seen following an identical feeding pattern on different nights. After feeding, the bat flies to a night roost to rest; favored night roosts include porches of houses, garages with open doors, or a breezeway.

Food Habits: The bats consume beetles, ants, flies, mosquitos, mayflies, stoneflies and other insects.

Reproduction: Mating occurs in autumn and winter, females store sperm, and fertilization takes place in the spring. In the eastern United States, big brown bats usually bear twins in early June. In the western United States, usually only one baby is born each year.

Status of Populations: Common throughout most of its range.

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.

New Mexico Energy, Minerals and Natural Resources Department | Copyright
1220 South St. Francis Drive | Santa Fe, NM 87505
Webmaster   |   EMNRD Legal Disclaimer