Every fall, these big brown bats (Eptesicus fuscus ... baring its sharp white teeth in protest. Slack gently loosens the bat’s claws from the rock and slips the four-inch-long animal into ...

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).