Bats

Bats are mammals of the order Chiroptera. Chiroptera comes from two Greek words, cheir or "hand" and pteron "wing". This name really gets to the essence of this remarkable order whose fingers have membrane(thin film) around them, making wings that can be very dexterously used for flight. These are the only mammals that can truly fly as well as birds. Some of them even migrate like birds do, in search of food.

a warm-blooded vertebrate animal of a class that is distinguished by the possession of hair or fur, the secretion of milk by females for the nourishment of the young, and (typically) the birth of live young

seriously at risk of extinction.

done, occurring, or active at night