Flight of Animals

motion of animals in the air by means of special organs of locomotion—wings. Most insects and birds, as well as some mammals (for example, bats), have the ability to fly. Flight was characteristic of the pterosaurs, a group of fossil reptiles.

Wings help create the aerodynamic forces (lift and thrust) necessary for flight. Flying animals possess a number of structural features that facilitate flying: widening of the tracheal system in many insects and air sacs and pneumaticity of bones in birds. Active flight consists in moving through the air by flapping the wings; passive flight involves gliding and soaring. Gliding is flying along a plane tilted downward. In so doing, the lifting force balances the weight of the body. Soaring is flying in an upward current of air (static soaring) or in a horizontal current of air using the uneven flow velocities in the different layers (dynamic soaring).

Insects are only capable of active flight. All birds can fly actively; many can also glide and soar. The flying speed of insects varies from 7.5–15 (Muscidae) to 54 km/hr (Sphingidae). Birds fly at the rate of 35–140 km/hr; the dive of a peregrine falcon can reach 300 km/hr.

The movement of some other animals through the air (for example, flying squirrels, flying fish) differs from flight.