The big free-tailed bat has brown to black fur, ears that meet in the middle of its forehead, and a long tail that extends beyond the tail membrane. Its habitat is in rocky canyons where this bat roosts in rock crevices and has been occasionally documented roosting in buildings and tree cavities. It is a strong flyer and migrates between winter and summer homes. Breeding colonies of the big free-tailed bat have been found as far north as Colorado. This species mostly feeds on moths but will sometimes eat other insects including grasshoppers, ants, and beetles. Mothers give birth to one pup a year.