Mission San Juan Capistrano plays bird calls to lure cliff swallows

Cliff swallows on a line.
Cliff swallows on a line.
Arthur Chapman/Flickr

The Mission San Juan Capistrano is trying a new way to charm cliff swallows back to nest at its stone church...through song.

Last week, the Mission started playing amplified loops throughout the day of the chirps that male birds make during courtship. The sound can last from four to six hours — and the clip of the song is itself 10 minutes long.

The birds used to come to the Mission every spring during migration, in a celebration known as the "miracle of the Swallows." But the number of birds has been decreasing every year for decades as urbanization threatens their nesting grounds.

The Mission plans to keep playing the calls through next month, saying that the method has worked before on other social birds.

So far, the Mission says some cliff swallows are feeding nearby, but they haven’t begun building their mud nests.