Fun Facts About Little Brown Bats

• Little brown bats, Myotis lucifugus, are abundant in southern Alaska, Canada, across the United States from the Pacific to Atlantic coasts, and the higher elevation forested regions of Mexico.
• The fur of Little Brown Bats is glossy, and varies in color from dark brown, golden brown, reddish, to olive brown. The wing and interfemoral membranes are nearly hairless and dark brown or black. Little Brown Bats have small ears and large hind feet. They are on average 3 1/2 inches long, with a wingspan of 9 inches with an average weight of 1/3 of an ounce.
• Typical life span is 6 years.
• Pups are born and reared in June and July after a 50 to 60 day gestation period. Young are born into the interfemoral membrane; only one young is born per year. The pups’ eyes and ears open within hours of birth, and deciduous teeth are fully erupted. Pups must cling to the female’s nipple using their deciduous incisors, large thumbs, and hind feet. The young start hearing at day 2 and develop auditory sensitivity similar to that of an adult by day 13. On approximately day 9.5, pups are able to thermoregulate and in three weeks they are able to fly.
• Little brown bats are primarily nocturnal and emerge from their roosts at dusk. Primary activity occurs about two or three hours after dusk and secondary activity may occur before dawn; most individuals return to the roost by four or five o’clock in the morning. These bats usually enter daily torpor. During the winter, hibernation time depends on altitude and location of the roosts. It usually starts between September and November and ends in March to May.
• Little Brown Bats catches free-flying insects in wooded areas, fields, and over water, but also preys on insects on the water surface. Insects caught during flight are taken by swooping or dipping maneuvers using echo location. Most activity over water occurs between 1 to 2 m over the surface and the insects are taken by the mouth. Most feeding activity occurs about two hours after dark.