They range in size from 6 to 12 in. Swifts have long wings and small feet and can perch only on vertical surfaces. They scoop up insects in their wide mouths while on the wing.
Swifts are the most rapid fliers known among living creatures.
In the United States the common eastern species is the chimney swift, Chaetura pelagica, miscalled chimney swallow. Its spiny tail acts as a prop when it clings to the chimneys in which it builds its nest of twigs, cemented with saliva. In the W United States are the black, Vaux's, and white-throated swifts. The common European swift is sometimes called hawk swallow. True swifts vary greatly in their nesting habits, some being cliff breeders, some using palm leaves for building their nests, and others nesting in chimneys.