D.C. Code § 1-167.31 – Official state mammal of the District of Columbia.

(a) The Big Brown Bat (Eptesicus fuscus) is a species of mouse-eared bat found throughout the United States, including the District of Columbia.
(b) Bats are the only flying mammals. The Big Brown Bat can fly up to 40 miles per hour, one of the fastest bats.
(c) The Big Brown Bat is considered large for an American bat, and has a wingspan of 12-16 inches and a weight of 14-21 grams. A big brown bat can live up to 18-20 years in the wild.
(d) The Big Brown Bat uses echolocation to forage for insects, preferring to eat beetles with its jaws that can chew through the hard exoskeletons, but also eating a variety of other insects including moths, flies, wasps, and flying ants that they capture in flight.
(e) The Big Brown Bat (Eptesicus fuscus) is hereby designated the official state mammal of the District of Columbia.

Dec. 23, 2020, D.C. Law 23-160, § 2