The Big Brown Bat (Eptesicus fuscus) is native to Virginia and can be found throughout the United States except for the State of Florida. These bats are one of Virginia's most common along with the Little brown bat. They are often found roosting in caves, forests, and hollow trees. Although, it is more common for them to be found in man made structures such as attics, churches, apartment complexes, warehouses and other buildings of Fairfax, VA. These bats are medium sized bat with a weight of 1/2 - 5/8 oz, length of 4-5 inches and an average wing span of 11-13 inches. They have long dark brown glossy fur, with a black muzzle, ears and wings. These bats are not an endangered federally protected bat, although they are still just as beneficial to the environment.
The Big Brown Bat can live to be more than 20 years old, although the average lifespan is thought to be between 18-19 years. They sporadically mate between November and March. After mating season the females will form small maternal colonies mostly in man made structures which often times are attics of Fairfax homes. The pups are between the months of May to early June. Within the State of Virginia the Big Brown Bat will often give birth to 2 pups as where in the western part of the U.S. they only give birth to 1 pup. These bats are not migratory and may choose to use the same hibernacula for summer and winter as long as there are no bright lights and the temperature remains stable between 32 and degrees Fahrenheit. This bat was also affected by the White Nose Syndrome of 2006 and 2007. Which was estimated to have killed millions of bats within the United States. Bat populations were estimated to have declined by 80% as a result of this devastating fungus.
These bats are insectivorous eating insects such as beetles, moths, wasps and other insects they can catch in flight. Many of the insects they feed on are harmful which makes them very beneficial to the environment.