The Ozark big-eared bat once lived in caves in Missouri, Arkansas, and Oklahoma. However, they have apparently abandoned their Missouri habitat due to human encroachment and cave disturbance.

The big brown bat is the Adirondack’s largest bat; only the hoary bat is larger. The long, lustrous fur is brown. The ears, wing and tail membranes are black. Total length is 105-123 mm (4.1-4.8 in).