Swallows  (Hirundinidæ) are birds with long pointed wings, small feet, short, broad bill, and ten tail feathers. About one hundred species are known, almost universal in distribution. They feed while flying, catching insects. Some build nests in crevices, some dig holes in banks, and others make mud nests plastered against walls. The Barn Swallow of the United States, much like that of Europe, is lustrous steel blue, pale chestnut below, tail deeply forked. It arrives early in May and remains until late August. The American Chimney Swallow is a Swift. The Purple Swallow, or Purple Martin is a North American species. The general color, both of the upper and under parts, is shining purplish blue; the wings and tail black. It is a universal favorite and is hailed as the harbinger of spring. The Republican Swallow or Cliff-swallow of North America, makes a nest of mud, in form somewhat like a Florence flask, which it attaches to a rock or to the wall of a house. Hundreds sometimes build their nests in close proximity.