Songwriter Leon Rene was listening to the radio one morning when he heard the announcer say the swallows were about to arrive at the Mission San Juan Capistrano, and an idea for a song was born. Rene is the author of "When the Swallows Come Back to Capistrano," which was introduced in 1939, and was soon a hit.

According to tradition, the swallows return to Capistrano on March 19th, St. Joseph's Day. They come from the Holy Land, says the legend, carrying a twig in their beaks, which they drop on the ocean when they want to rest during their journey. As romantic as the legend sounds, it isn't true; ornithologists have tracked the birds to Argentina where they spend the winter, returning in the spring to raise their young.

The Capistrano birds are cliff swallows, which have probably been returning to the area for centuries. They transferred their nests to the eaves of the Mission when it was built as a result of its convenient location near two rivers, which they needed for mud. Swallows build their nests out of tiny granules of mud piled on top of one another, to form an inverted pouch with a funnel-like opening. They return to the same nests each year and if the nests haven't survived the winter, they often rebuild in the same place.

As San Juan Capistrano has grown, the swallows have found more eaves to nest under, yet their food supply has dwindled. Insects necessary to their survival thrive in open fields, particularly those near riverbeds. The reduction in numbers of the insects (as a result of the development of the area), has caused the swallows to locate further from the center of town, which explains why visitors no longer see clouds of swallows descending on the Mission, as they once did.

Swallows are still Capistrano's most famous citizens, well-known and well-loved, protected in San Juan Capistrano by ordinance, which declares the city a bird sanctuary. Romantics all over the world consider the swallows one of the best remains of the colorful past of early California.