SWIFTS, birds of the. family Micropodide (or Cypselida,), noted for the extreme rapidity of their flight. Their proper place in the system of ornithology has been much discussed. For merly they were universally classed with the swallows, but the usual opinion among ornithol ogists is that, unlike as are the swifts and hum ming birds (q.v.) in general aspects, they with the nightjars form a natural assemblage, the order Cypseliformes, or its equivalent. The swifts have a generally awallow-like aspect. The bill is very small, flat and weak, but the mouth, which is not provided with bristles. tends far back beneath the eyes, giving a very extensive gape. Just at its base above are the nostrils partly covered by feathers. The feet are very small vrithout any distinct scaly cover ing or any conrb-like claws, and they present remarkable peculiarities in the position of the hallux and the number of phalanges in the dif ferent genera. The wings are extremely long, reaching far beyond the tail and crossing, but the length lies entirely in the extremely elon gated pritnary quills, the upper segments of the arm and the secondary quills being unusually small. In the typical swifts the tail is long and forked, in others it is short, truncate and spiny; there are always 12 retrices. Among anatomical characters swifts have the salivary glands remarkably developed arid of the mucous type; the lower intestine has no cmca ; the skull lacks basipterygoid processes in those which have the palate of the passerine (cegithognath ous) type but has them combined with the cleft-palate (shizognathous)' -type; the keel of the sternum is remarkably deep and the pectoral muscles correspondingly well developed. Ex cept that they shun the polar regions these strictly insectivorous birds are cosmopolitan in their distribution. There are about eight genera and 75 species divided into the subfamilies of Micropodince or typical swifts and the Chatur int', or spine-tailed swifts. The first has the tail feathers normal, the tarsi and toes feath ered, the bind toe capa:ble of being turned later 'ally or forward and the three front toes with only three joints each. Nearly all of the spe .cies of this group belong to the Old World, several being South American, and one belong ing to the United States. In Cypse/us all four toes are directed forward. To this genus be long the common swift of Europe (C: apus) and the Alpine swift (C. alpinus). The only representative of this group occurring within the United States is white-throated or rock swift (Aironautes melanoleucus), found in the southwestern region north to Wyoming and in winter in Mexico and Central America. The hind toe is directed laterally, not forward, and the foes are only partially feathered. The colors are black above with some white mark ings and white below; the length about seven inches and the closed wing the same. This
species is gregarious and nests in extensive colonies in holes and on ledges of inaccessible cliffs. Like the European swift its flight is incredibly rapid. Among exotic species of true swifts, none are of greater interest than palm swifts (Tachornis) of Africa and the tropical Orient and the aberrant tree swifts (Macrop teryx) of India and Ceylon, which nest in trees.
The subfamily Cheturina, has the feet more normal, but the hind toe is more or less versa tile and the phalanges of the front toes, though not reduced in number, are extremely short; the feet are unfeathered and the tail feathers have the vane wanting at the end, the produced shaft forming a stiff mucronate tip. The com mon chimney swift (or erroneously swallow) (Chatura pelagica) is an example, and is too well known to require a description. It is a migratory species and one of the very latest birds to appear in summer. It breeds as far north as Labrador and winters southward to southern Mexico. Its western limit is the cen tral plains. This is one of the birds which has been reputed to hibernate at the.bottom of ponds and not a few circumstantial accounts of the manner in which they entered the mud have been published. Several patient, truth-loving, zoologists have carefully investigated these re ports with the expected result that they proved baseless. The nests of this swift are interest ing structures of twigs glued together with a thick coating of hard varnish-like dried saliva, which also serves to attach the saucer-like struc ture to the inside of an unused chimney, which at the present time are the altnost ex clusive nesting and sleeping sites of these birds. Formerly they occupied hollow trees and still do in unsettled parts of the country. The eggs are pure white and number four or five. Most of the life of these birds is spent in flight, and many and remarlcable are their aerial per formances. The only other swifts of this sub family inhabiting the United States are Chatura vauvii of the Pacific States, there re placing the eastern chimney swift, and the black swift (Cypseloides niger) of the Rocky Mountain region and westward from British Columbia to Central America. It ascends to great altitudes. Several species of the latter genus occur in South America. Callocalia in cludes the edible birds'-nest swifts (q.v.) of which a number of species occur from south eastern Asia to Madagascar and the Marquesas.
Consult, besides the articles referred to above, and the standard works on American Ornithology, especially Hartert, 'Catalogue Birds British Museum' (Vol. XVI, London 1892) and (Cambridge Natural History' (Vol. IX, New York 1907).