kilometers.

The wingtip bones of swiftlets are of proportionately greater length than those of most other birds. Changing the angle between the bones of the wingtips and forelimbs allows swifts to alter the shape and area of their wings to increase their efficiency and maneuverability at various speeds. They share with their relatives the hummingbirds a special ability to rotate their wings from the base, allowing the wing to remain rigid and fully extended and derive power on both the upstroke and