Migration Info The relatively leisurely migration of these swallows begins in early February, when they begin passing along the eastern slopes of the Andes. They follow the Gulf coast into northern Mexico and then split into two groups. Western populations move rapidly up the Pacific coast, while eastern birds push into the Mississippi River valley and northward. There is some evidence that individuals that nest together in North American colonies remain together while leading a primarily nomadic existence in South America.
This is the famed swallow of Mission San Juan Capistrano, reputed to arrive each year on exactly March 19 (St. Joseph's Day). The birds actually reach southern California much earlier than that in most years. It is also interesting to note that in artistic depictions of the swallow's return to this historic mission, the pictures often depict Barn Swallows, which possess long forked tails that are more aesthetically pleasing than the short gray tails of Cliff Swallows.