Swifts make up the family Apodidae. The name of this family comes from the Greek and means "without feet".
Together, swifts and hummingbirds make up the order Apodiformes. These birds do have feet, but they have very short legs and use their legs and feet only for perching. They do not walk. Instead, they fly from place to place.
Swifts are among the fastest birds in the world.
The common swift (Apus apus) can fly faster on its own power than any other bird in the world, as far as scientists know. It can reach a speed of 69 miles per hour when flying horizontally, unassisted by gravity.
Swifts can be found in arctic and temperate regions throughout the world. They live on every continent on Earth, except Antarctica. Some are migratory and spend their winters in the tropics.
Some swifts enter a state of torpor, in which their metabolic rates are greatly reduced, when the weather is cold for a short amount of time.
Swifts eat insects and spiders, which they catch in flight.
They build nests on cliffs, on cave walls, or on tall structures, such as chimneys. Because they do not walk, they need to be able to fly directly from their nests.Swiftlets
Swiftlets, also known as cave swiftlets, are a group of swifts that live in tropical and subtropical areas of Asia, Australia and the islands of the South Pacific. They breed and roost in caves.
The nests of some species of swiftlet are used to make bird's nest soup, a highly prized Chinese dish. These nests, which are attached to the walls of caves, are made of the swiftlets' saliva, sometimes combined with small amounts of grass, lichens and bark.
Some swiftlets use echolocation to find their way around the caves in which they live. They navigate by making clicking noises and then listening to the echoes that are produced.