About Bird Wings

A bird's wings are its forelimbs. They are the most important body part of a bird as they enable flying, a definitive bird characteristics. And even though not all birds actually fly, all birds have wings. The aerodynamics of a bird's wings determine flying speed, flexibility and the energy required for flight.

  1. Structure

    • Bird wings have three limb bones: humerus, ulna and radius. The manus, also known as the "hand" of a bird, serves the principle purpose of acting as an anchor for the set of feathers called primaries, whereas the other set of feathers--located on the ulna behind the carpal joint--are called the secondaries. The rest of the feathers on the wings are termed "coverts."

    Function

    • A bird's wing is shaped like an airfoil, where the upper part is more or less in a convex shape as compared to the lower part. While a bird cuts through the air and moves forward, the trail of air passing above the wing is longer as compared to the air below the wing. The velocity of air passing above is also higher than the air below the wing and, as a result, a low pressure is created above the wing that provides lift to the bird, enabling it to fly.

    Significance

    • The shape of the wings plays a significant role in the kind of flight that a particular bird is capable of. Several aspects, such as speed, maneuverability and energy use, depend on the wing shape. The shape of the wing itself, also known as planform, depends on two parameters: wing loading and aspect ratio. The former determines the ratio of the weight to the area of the wing, and the latter is the ratio between the wingspan and the mean of the chord (the name for the width of the wing).

    Types

    • Bird wings can be broadly categorized into four distinct types: elliptical wings, high aspect ratio wings, high speed wings and soaring wings with slots. Elliptical wings are usually found in areas with dense vegetation; they are round and short wings. Wings with high aspect ratio are much longer and wider and are usually used for hovering. High speed wings have a pointed edge and are comparatively short. The fourth type of wings is found in birds of larger species like the vulture and eagle.

    Flapping Speed

    • The flapping speed of each bird depends on its size and the shape of its wings. Larger birds such as vultures have a flapping speed of one flap per second, whereas smaller birds flap four times per second. The hummingbird has a flapping speed of ten flaps per second and has a flying speed of 60 mph.