Bats are the only mammals naturally capable of flight.
Bats are mammals of the order Chiroptera ( [ kaɪˈrɒptərə ] from the χείρ - cheir , `` hand '' and πτερόν - pteron , `` wing '' ) whose forelimbs form webbed wings , making them the only mammals naturally capable of true and sustained flight . Bats are the only mammal capable of true flight .