swifts are fastest flight speeds of any bird.

 The swift is a enigmatic little bird spends almost its entire life air borne. It medium-sized aerial bird, which is a superb flier. It evens sleeps on the wing! It is plain sooty brown, but in flight against the sky it appears black. It has long, scythe-like wings and a short, forked tail. A bird best identified by silhouette, the smudge-gray Chimney Swift nimbly maneuvers over rooftops, fields, and rivers to catch insects. Its tiny body, curving wings, and stiff, shallow wing beats give it a flight style as distinctive as its fluid, chattering call. This enigmatic little bird spends almost its entire life airborne. When it lands, it can’t perch—it clings to vertical walls inside chimneys or in hollow trees or caves. It is a summer visitor, breeding across the UK, but most numerously in the south and east.
It winters in Africa. Look up in the sky in summer, often very high. They never perch on wires like swallows. You might see excited screaming parties of them careering madly at high speed around rooftops and houses, often low, especially towards dusk. Closely resembling swallows, swifts range in length from about 9 to 23 cm (3.5 to 9 inches). They have exceptionally long wings and chunky, powerful bodies. Their compact plumage is a dull or glossy gray, brown, or black, sometimes with pale or white markings on the throat, neck, belly, or rump. The head is broad, with a short, wide, slightly curved bill. The tail, although often short, may be long and deeply forked. The feet are tiny and weak; with the aid of sharp claws they are used only to cling to vertical surfaces. A swift that lands on flat ground may be unable to regain the air. In soft-tailed forms, the hind toe is rotated forward as an aid in gripping vertical surfaces; in spine-tailed swifts, support is gained from the short needle-tipped tail feathers, and the feet are less modified.
swift,  any of about 75 species of agile, fast-flying birds of the family Apodidae (sometimes Micropodidae), in the order Apodiformes, which also includes the hummingbirds. The family is divided into the subfamilies Apodinae, or soft-tailed swifts, and Chaeturinae, or spine-tailed swifts. Almost worldwide in distribution, swifts are absent only from polar regions, southern Chile and Argentina, New Zealand, and most of Australia.
In feeding, swifts course tirelessly back and forth, capturing insects with their large mouths open. They also drink, bathe, and sometimes mate on the wing. They fly with relatively stiff, slow wingbeats (four to eight per second), but the scimitar-like design of the wing makes it the most efficient among birds for high-speed flight. The fastest of small birds, swifts are believed to reach 110 km (70 miles) per hour regularly; reports of speeds three times that figure are not confirmed. The only avian predators known to take swifts with regularity are some of the larger falcons.
Among the best-known swifts is the chimney swift (Chaetura pelagica), a spine-tailed, uniformly dark gray bird that breeds in eastern North America and winters in South America, nesting in such recesses as chimneys and hollow trees; about 17 other Chaetura species are known worldwide. The common swift (Apus apus), called simply “swift” in Great Britain, is a soft-tailed, black bird that breeds across Eurasia and winters in southern Africa, nesting in buildings and hollow trees; nine other Apus swifts are found throughout temperate regions of the Old World, and some Apus species inhabit South America. The white-collared swift (Streptoprocne zonaris), soft-tailed and brownish black with a narrow white collar, is found from Mexico to Argentina and on larger Caribbean islands, nesting in caves and behind waterfalls. The white-rumped swift (Apus caffer), soft-tailed and black with white markings, is resident throughout Africa south of the Sahara. The white-throated swift (Aeronautes saxatalis), soft-tailed and black with white markings, breeds in western North America and winters in southern Central America, nesting on vertical rock cliffs.

Some species of swifts are among the fastest animals on the planet, with some of the fastest measured flight speeds of any bird