Luring Swallows Back with a Love Song

Toy swallows are for sale at mission in San Juan Capistrano, Calif., Thursday, April 26, 2012. For most of its 230-year history, the Mission at San Juan Capistrano has been known for the cliff swallows that flock to the crumbling bell tower each spring to nest. In recent decades, however, what used to be swarms of swallows at the original Spanish mission have dwindled. (AP Photo/Chris Carlson)

Swallows in flight over sunset.

An empty swallow nest hangs in the eves of the roof at the mission in San Juan Capistrano, Calif., Thursday, April 26, 2012. For most of its 230-year history, the Mission at San Juan Capistrano has been known for the cliff swallows that flock to the crumbling bell tower each spring to nest. In recent decades, however, what used to be swarms of swallows at the original Spanish mission have dwindled. (AP Photo/Chris Carlson)

Swallows are outlined in the stone work at the mission in San Juan Capistrano, Calif., are seen Thursday, April 26, 2012. For most of its 230-year history, the Mission at San Juan Capistrano has been known for the cliff swallows that flock to the crumbling bell tower each spring to nest. In recent decades, however, what used to be swarms of swallows at the original Spanish mission have dwindled. (AP Photo/Chris Carlson)

Speakers hidden behind the statue call to swallows at the mission in San Juan Capistrano, Calif., Thursday, April 26, 2012. For most of its 230-year history, the Mission at San Juan Capistrano has been known for the cliff swallows that flock to the crumbling bell tower each spring to nest. In recent decades, however, what used to be swarms of swallows at the original Spanish mission have dwindled. (AP Photo/Chris Carlson)

Visitors wait for swallows to arrive at The Mission San Juan Capistrano in California. (AP)

A swallow veiwing area is set up to watch nesting birds at the mission in San Juan Capistrano, Calif., Thursday, April 26, 2012. For most of its 230-year history, the Mission at San Juan Capistrano has been known for the cliff swallows that flock to the crumbling bell tower each spring to nest. In recent decades, however, what used to be swarms of swallows at the original Spanish mission have dwindled. (AP Photo/Chris Carlson) (AP2012)

Man-made nests hang in the eves at the mission in San Juan Capistrano, Calif., Thursday, April 26, 2012. For most of its 230-year history, the Mission at San Juan Capistrano has been known for the cliff swallows that flock to the crumbling bell tower each spring to nest. In recent decades, however, what used to be swarms of swallows at the original Spanish mission have dwindled. (AP Photo/Chris Carlson)