The Cliff Swallow, Petrochelidon pyrrhonota, is a member of the perching bird family Hirundinidae. It breeds in North America and Mexico, and is migratory, wintering in southern South America. This species has always been plentiful in the west of North America, where there are many natural sites, but the abundance in the east has varied.
These birds average 5 inches long with a tiny bill. The adult has a shimmering blue back and crown, brown wings and tail, and buff rump.
The nape and forehead are white. The underparts are white except for a red face. The tail is square-ended. Young birds are essentially brown above and whitish below, except for the buff rump and dark face.
Cliff Swallows breed in large colonies. They build conical mud nests and lay 3-6 eggs. The natural nest sites are on cliffs, preferably beneath overhangs, but as with the Eurasian House Martin, man-made structures are now the principal locations for breeding. Female Cliff Swallows are known to lay eggs in and move previously laid eggs into the nests of other birds within the colony.
Cliff Swallows are the famous swallows that return every year to the
Mission San Juan Capistrano in California on (or around) March 19.