Big Brown Bat

Scientific Name: Eptesicus fuscus

Weight: 11-23 grams

Wingspan: 32-35centimeters

Distribution: From southern Canada throughout the United States to northwestern South America, including many islands in the Caribbean.

Ecology and Behavior: Big brown bats are closely associated with humans and are probably more familiar to 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 stay during winter remains unknown. This species emerges at dusk and flies a steady nearly strait course at a height of 6-10 meters. Its large size and steady flight make it easily recognizable. Apparently, some individuals use the same feeding ground each night, for a bat can 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 the porches of stucco or brick houses, garages with open doors, or a breeze way.

Food Habits: These bats consume beetles, ants, flies, mosquitoes, mayflies, stoneflies, and a variety of other insects.

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

Status of Populations: Relatively common throughout most of its range.