It is a Big Brown Bat (Eptesicus fuscus).
The big brown bat (Eptesicus fuscus) is a widespread species of bat found throughout North America, Central America, the Caribbean, and extreme northern South America.
It is a relatively large microbat, weighing 15–26 g (0.53–0.92 oz).
Adult body length is 110–130 mm (4.3–5.1 in). Its forearm is usually longer than 48 mm (1.9 in). Its wingspan is 32.5–35 cm (12.8–13.8 in). Its dorsal fur is reddish brown and glossy in appearance; ventral fur is lighter brown. Its snout, uropatagium, and wing membranes are black and hairless. Its ears are also black; they are relatively short with rounded tips. The tragi also have rounded tips. Its dental formula is
, for a total of 32 teeth.
One study of a population in Colorado found that their average life expectancy was a little over 6.5 years; the oldest known big brown bat was 19 years of age (!) and documented in Canada.