This species is the largest bat native to North America, and some of its distinguishing characteristics are its large ears, wings, and forearms.

In South America, the species is found in Brazil and its neighboring countries, ranging southward to northern Argentina.

[7] Roosts are commonly located in crevices of rocky areas, such as cliffs and canyons,[6] and have also been found within man-made structures such as buildings and tunnels.

[8] Western mastiff bats are nocturnal, leaving roosts at night to find food.

[6] Unlike most North American bats, they do not undergo either migration or prolonged hibernation, but are periodically active all winter.

[9] One notable characteristic of this species is its high pitched echolocation call, as it can be heard from heights of 990 feet (300 m).

Moths are its biggest food source, but it has been observed to eat beetles, ants, dragonflies, crickets, and grasshoppers.

[2] The loss of cliff sites as a result of urban/suburban development and activities such as water impoundments, highway building, and quarry operations has also contributed to the species' endangered status, making it harder to find adequate roost places.