The only mammals who have mastered the airspace - a bat. There are about a thousand different species.
They come in all sizes, from the smallest bat mouse weighing only 2 grams, to huge, with a wingspan of nearly two meters.
Bats sleep during the day, clung to a branch or rock upside down. Hunting fly only at night or at dusk. Most mice eat insects, which are detected by sonar. The animals make sounds that a person can not hear, catch the reflected sound huge ears and so detect prey or obstacle.
Many bats, like birds fly to winter in warmer climes, where there is no severe frosts. For example, large moth fly from Ukraine to Hungary in the fall, and the North American laziurusy spend the winter on the shores of Florida and Bermuda. Some species of bats hibernate. They gather in caves, attics of houses, closely pressed against each other for warmth.