The big brown bat, Eptesicus fuscus, is a common bat that occurs throughout most of North America. It is one of the most widespread and abundant bats in Utah; it can be found state-wide, with the possible exception of the West Desert area. Preferred habitats for the species include woodland and urban areas. The species is nocturnal - daytime roosting occurs in buildings, caves, mines, rock crevices, and trees. Big brown bats are often solitary, but may congregate into small colonies during the spring and summer.
Females give birth to one, possibly two, young in late spring. Big brown bats eat flying insects, especially beetles. They usually forage just after sunset, often over water, near trees, or near artificial lights. Although some big brown bats may migrate to escape cold weather, most individuals hibernate during the winter months.