Swift (bird)

Swift (bird), common name for any of more than 90 species of a family of birds that includes some of the fastest flyers known. Swifts superficially resemble swallows. They have a short bill; a wide, gaping mouth for feeding on insects on the wing; small, weak feet; and long, crescent-shaped wings. Swifts nest along vertical surfaces, building their nests of various materials glued together with a cementlike substance secreted from their salivary glands. Some species of the Oriental swiftlet make their nests entirely of this secretion, which is the principal ingredient of so-called birds' nest soup. Most swifts are tropical; only five species breed in North America, of which the best known is the chimney swift. It is sooty brown above and lighter beneath, usually attaining a length of 14 cm (5.5 in). The common swift of Europe is larger, 16.5 cm (6.5 in), blacker, and has a forked tail; it often nests in city buildings.

Scientific classification: Swifts belong to the family Apodidae in the order Apodiformes. The chimney swift is classified as Chaetura pelagica and the common swift of Europe as Apus apus.