Systematics of the Swallow family:
Brief description of the family
Swallow - small (length 9-23 cm, weight 10-60 g), perfectly flying sharp-winged birds with a typical appearance. The nature spreading almost cosmopolitans who did not penetrate only Antarctica, New Zealand, small oceanic islands and the regions of the Arctic and Subarctic.
A rounded, slightly flattened head with a short, rather distinctly flattened beak; the mouth is very large (the jaw joint is at eye level). The bronchial rings are more or less closed, and in the region of the lower larynx there are half rings. The salivary glands are very large (enlarge before nesting). The wings are long, pointed, with 9 primary flight feathers, of which the longest are the first and the second (in fact, the second and third, if we take into account the rudiment of the first flight). There are twelve helmsmen. Tail with a more or less sharp cut. The legs are rather weak, with short tarsus and thin toes. They walk slowly and reluctantly on the ground. The coloration is dark above and light (white) below. Gender and age morphismcoloration expressed indistinctly and not in all species. Usually one molt per year: full post-nesting. The plumage is dense, usually with a metallic shade on the upper side. The long and sharp wings allow the swallows to fly through the air with extreme ease, speed and indefatigability.
Inhabited by predominantly open landscapes: river valleys in the plains and in the mountains, coasts, forest edges, many species are synanthropus. Males have a chirping song. Nests most species are stucco, from lumps of dirt, held together by saliva and attached to rocky cliffs, trees, buildings. Some species dig holes in cliffs, others nest in hollows and crevices of rocks. In many species, nesting is colonial or group. The nest tray is always lined with soft plant rags and feathers. In clutch there are 3-7 eggs, usually white, sometimes with specks. Incubation 13-20 days. In many species, the female incubates more intensively than the male. Chicks hatch naked or slightly pubescent. 3-5 weeks remain in the nest. Some species have 2-3 clutches per season. Outside the breeding season, they keep in flocks. Nomadic in the tropics, migratory in temperate latitudes.
Food they consist of insects, which they grab on the fly, and unlike swifts, they not only grab flying insects, but can also grab those sitting on walls, rocks, etc. swallows arrive earlier and later fly away than swifts (the latter catch only flying insects, and the flight of the latter is inextricably linked with temperature), due to the great perfection of the swallow's eye accommodation.
Center of origin, apparently, Africa, where most of the species are now found. For example, 15 species of swallows nest in Angola. In South America, the species composition of swallows is more diverse than in North America. Some species have very large ranges: for example, the barn swallow Hirundo rustica L. and sand martin R. riparia (L.) are widespread in Europe, Asia, North America, and in some places in North Africa. In the CIS, 9 species of 6 genera are recorded, 7 species of 4 genera undoubtedly nest.