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big brown bat

(Eptesicus fuscus fuscus)


This is a large, dark brown bat with long, glossy fur, a broad nose and wings, and short, black ears. The average total length is 103-130 mm, with a weight of 13-18 grams (0.4 – 0.6 ounces). There are usually 2 young born in a nursery colony in late May-early June. Nursery colonies are usually located in manmade structures, such as barns, houses and churches. They fly strong, nearly straight courses at about 20-30 feet. They are usually solitary or in small groups. It often uses man’s habitats and, because they are less tolerant of heat , they are often forced to move (e.g. to a basement) causing even more contact with man. They are not migratory like other bats and can use the same roost for both summer and winter. Light (unless very bright) and air movement were the limiting factors in hibernacula selection. The longevity record is 19 years. Predators include rat snakes, hawks, screech owls, common grackles, long-tailed weasels, house cats and bullfrogs. This is the most common bat to enter a house through the fireplace.


The winter and summer range is identical. The big brown bat can be found through out the state of Virginia. This is one of two species that roosts in caves in the summer, but it is found most often in manmade structures.


These bats are efficient feeders, and fill their stomach in about an hour. The feeding habits are beneficial to man since many of the food insects are harmful. They feed mainly on beetles and other insects.