Swallows and martins form a well-marked and familiar group of birds. The only other family with which it is possible to confound them is that of the swifts. Anatomically the two families are far removed from one another; but similarity of profession has brought about similarity in outward appearance. Nevertheless, the representatives of the two families may be distinguished at a glance as they dash through the air. “As a swallow darts along,” writes Eha, “its wings almost close against its sides at every stroke, and it looks like a pair of scissors opening and shutting. Now a swift never closes its wings in this way. It whips the air rapidly with the points of them, but they are always extended and evenly curved from tip to tip, like a bow, the slim body of the bird being the arrow.” Jefferies likens a flying swift to an anchor with enormous flukes. Another difference between the swifts and the swallows is that the former never perch on trees or wires or on the ground, while the latter habitually seat themselves on branches of trees and telegraph wires.
A small bird that dashes with great speed through the air, frequently changing its course, flying now high up, now just skimming the ground, and seeming never to tire, can be nothing other than a swift or a swallow. By the tests given above it is easy to determine whether any particular bird is a swift or a swallow, but having got thus far it is a matter of greater difficulty to determine the species. (Illus. F. II., p. 267; also B. B., p. 35.)
Twenty-two species of swallow are found in India; of these the following are most commonly seen:
[86]. Cotile sinensis: The Indian Sand-martin. (F. 809), (J. 88), (-I.)
A tiny swallow, only about two-thirds the size of the sparrow. Upper plumage greyish brown. Chin and breast greyish white, rest of lower plumage white.
It nests in sandbanks, frequently in company.
Occurs only in N. India.
[87]. Ptyonoprogne concolor: The Dusky Crag-martin. (F. 811), (J. 90), (-I.)
Upper plumage dark brown. Some white spots on the tail. Lower plumage dark brown, paler on the breast. The most dull-coloured of the swallows. It builds a nest like that of the common martin—a saucer of mud stuck on to some vertical surface, usually a cliff or the wall of a cave.
[88]. Hirundo rustica: The Common Swallow (F. 813), (J. 82), (I, but with a deeply forked tail 4½ inches in length.)