Wings

The bend you can see along the front of this red kite's wing is its wrist

Birds' wings are really front legs covered in feathers. But, unlike the front legs of other animals, they don't support the bird's weight on the ground. Instead they can lift birds into the sky and keep them up there. No human machine can fly as effectively and efficiently as a bird's wing.

Arm adaptations

One look at a bird’s skeleton shows how its wing is similar to our arms. But there are some important differences. The upper arm is short and thick, for powering the wing beat: this part is invisible on most birds. The bend in the middle of the wing is actually the bird’s wrist. The last joint of the wing is like our hand, but it has only one finger bone. This holds all the long primary feathers used for flying.

Tucked away

The main flight feathers of this roseate tern stick out near its tail

A bird’s wings are no use on the ground, so it folds them away neatly when it lands. You can see the main flight feathers folded on either side of its body. On birds with longer wings, the tips of the primaries stick out near its tail. The bird’s ‘shoulders’ that appear either side of its breast are actually its wrists.