A bird can fly for the same reason that an airplane can fly -- the pressure of the air on top of its wings is less than the pressure below. When the bird's wings move forward, the air must travel farther and faster over the curved top surface of the wings than it does over the bottom surface. The pressure on top of the wing is less than the pressure below, because of this difference in the speed of the air.

The wing feathers overlap on the downstroke and push against the air. On the upstroke, the feathers twist open, allowing the air to pass through and making it easier to lift the wing.

Air flowing over the top of a bird's wing decreases in pressure, but the air under the wing maintains a constant pressure. This difference in air pressure helps lift the bird in flight.

Questions or comments about this page?

This page was last updated on June 07, 2017.