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Big Brown Bat

Photo Credit: Merlin D. Tuttle, Bat Conservation International

SCIENTIFIC NAME: Eptesicus fuscus
OTHER NAMES: night owl bat
DESCRIPTION. Big brown bats are one of the largest North American bats. They average 4 - 5 inches in length and weigh 0.5 -1.2 ounces at adulthood with wingspans of 12-16 inches. These bats have a glossy brown color on the back and a lighter belly color. They have small rounded black ears that are leathery in texture and nearly hairless. The wing membranes and tail are also black. Their heads are rather large with a broad nose and fleshy lips.
DISTRIBUTION. The big brown bat is one of the most common bat species in North America. It can be found from northern Canada throughout the United States and Mexico. Big brown bats are commonthroughout Alabama.
HABITAT.  Big brown bats occupy almost all habitat types. They seem to do well in forests, open areas, suburban, and urban areas. Big brown bats will roost under loose bark of trees, in caves, buildings, bat houses, and even under bridges. These bats are the most likely species of bats that people will encounter due to their abundant numbers and their ability to live in close proximity to humans. Big brown bats are year round residents in Alabama.
LIFE HISTORY AND ECOLOGY.  Big brown bats sleep during daylight hours and emerge from their roosts at dusk to feed throughout the night. They are insectivorous mainly foraging on beetles with their rather large and powerful teeth. They will also consume other flying insects such as flies, moths, wasps, and flying ants, which they capture while in flight. The big brown bat is considered to be one of the fastest species of bats reaching speeds of up to 40 mph. Mating occurs during the fall and early winter before hibernation. During this time females form maternity roosts, and males roost alone or in small groups. Females store sperm, and fertilization takes place in spring. Females give birth between late May and early July to one or two young that are born naked, blind, and deaf. Within a few hours their eyes and ears open. They are able to fly within six weeks and become independent within a few weeks of first flight. Maternity colonies disperse once the young become independent.   
Big brown bats can and do contract and transmit rabies.  Incidence of rabies in big browns is low, but contact with bats should be avoided, especially if the bat looks sick or is unable to fly. Big brown bats are very beneficial to both the environment and humans. They, like all bat species in Alabama, help control insect populations.
AUTHOR: Stewart Abrams, Wildlife Biologist, Alabama Division of Wildlife and Freshwater Fisheries, August 2012

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