Wing shape affects takeoff, speed and the height that a bird can reach during flight. One factor in all bird wings that affects flight is the low-aspect ratio, which is the ratio of length to width. Low-aspect ratio is good for rapid takeoff and allows the bird to quickly escape from predators, but does not allow for sustained speed.
Four common wing shapes found in birds include passive soaring wings, active soaring wings, elliptical wings and high-speed wings. The passive soaring wings have long feathers with slots that allow a bird to catch vertical columns of hot air called thermals. Doing so allows them to rise higher in the air. Eagles, hawks and storks are all examples of birds that posses passive soaring wings.
Active soaring wings allow birds to soar for long periods of time. Gulls and gannets are two examples of birds with active soaring wings. Birds with active soaring wings are more dependent on wind currents than those with passive soaring wings.
Elliptical wings enable a bird to sustain high speeds for short periods of time. Ravens, blackbirds, crows and sparrows are all birds that possess elliptical wings. Like active soaring wings, high-speed wings are long and thin. They enable the bird to maintain high speed for long periods of time. Examples of birds with high-speed wings include falcons, ducks, terns and swifts.