CLIFF SWALLOW (Calypte anna) Description: Has pointed wings and slender body as all swallows do; differentiated from other species by squarish tail and buffy rump. Most cliff swallows have a dark chestnut and blackish throat and pale forehead. Habitat: Common around bridges, rural settlements, and in open country on cliffs; require a source of mud for nest construction. Diet: Catches insects on the fly; occasionally gorges on berries. Displays: Courtship flight, followed by copulation on ground. Nest: Colonies of up to 1,000 pairs build nests of mud pellets on underside of bridges or culverts, walls under eaves, cliffs or other vertical surfaces. Eggs: White, creamy or pinkish white, spotted with brown; less than one inch long. Natural history notes: Each year on March 19, St. Joseph's Day, thousands of visitors descend on Mission San Juan Capistrano to welcome the cliff swallows back from their wintering grounds in Argentina. The birds aren't really as punctual as legend has it (they can arrive weeks before their official reception) and they are not as plentiful as they once were, but the story of their annual return to the old mission is known all over the world. Breeding bird atlas: To report bird breeding activity in your neighborhood, or to get information on the breeding bird atlas (now in its fifth and final year), call Sea and Sage Audubon Society members Sylvia Gallagher, (714) 962-8990, or Nancy Kenyon, (714) 786-3160. Note: Map is divided into 5-kilometer squares so that Audubon Society volunteers can more easily survey areas on a regular basis. Sources: Sea and Sage Audubon Society; "The Birder's Handbook," Ehrlich, Dobkin and Wheye, Fireside Books (1988); "Field Guide to the Birds of North America," National Geographic Society (1987); "Birds of Southern California: Status and Distribution," Garrett and Dunn, Los Angeles Audubon Society (1981). Indicates 5-kilometer-square areas where breeding activity has been confirmed.