Cliff Swallows build their mud-and-grass nests on cliff edges or beneath bridges, eaves, and culverts. To make the artificial nests as alluring and prominent as possible, workers at Mission San Juan Capistrano in California mounted the man-made structures under the arch of a temporary wall. Photo: Troy Harvey

Flock Together

A Homecoming for the Legendary Swallows of Mission San Juan Capistrano?

Artificial nests and recorded calls could lure the birds back to their celebrated nesting grounds in California.

Long ago, shopkeepers in Southern California resorted to violence to drive out their pesky neighbors—the Cliff Swallows. The owners became so aggravated by swallows nesting on their buildings that they destroyed their mud homes. The displaced birds found refuge at the Mission San Juan Capistrano, where they built new nests in the eaves of the ancient stone church. Ever since, the birds have returned on March 19, St. Joseph’s Day, to raise their young within the safety of the mission walls; then, on October 23, San Juan’s Day, they leave for their wintering grounds in Argentina, circling once to bid the haven goodbye. Or so the legend goes.

In reality, the birds do start arriving in the area in March, if not miraculously all on a single day. Since the early 1930s the people in the city of Capistrano have held a festival on the 19th to celebrate their return. Today, the event, which features ringing of the mission’s historic bells, Flamenco dance performances, food, and more, draws tourists from throughout the United States and abroad. But in recent years, the once-abundant guests of honor have been conspicuously absent.

Swallow numbers at the mission began to drop in the 1990s, after workers removed their nests during a restoration project on the church. Some moved to other structures, including a nearby housing development, but so far none have returned to the stone church where hundreds once nested. 

To try to lure the birds back, the mission turned to Charles Brown, a Cliff Swallow expert at the University of Tulsa. First, Brown tried wooing them with song. Each spring since 2012 he’s played a continual loop of swallow vocalizations on the mission grounds. The graceful aerialists have swooped in, presumably to investigate, but none have been convinced to settle down and construct a nest thus far.

This year Brown expanded the effort by adding a visual cue—artificial nests. “It’s known that Barn Swallows, and probably Cliff Swallows, are attracted to sites that have old nests,” he says. In addition, Brown has seen Cliff Swallows move into plaster nests he placed into existing colonies in Nebraska, though it took a couple of years for the birds to take up residence.

During the most recent festival, the mission unveiled a new 15-by-15-foot temporary wall attached to the old church holding about a dozen nests made from dental plaster. “Our hope is that if the birds move in, they will spill over and start using the actual mission structures, and eventually the wall could be phased out,” says Brown.

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Charles Brown and Megan Dukett, the mission’s education and interpretive program manager, discuss construction of the plaster nests, which were made from a mold created by one of Brown’s grad students. Photo: Troy Harvey
The artificial nests were constructed by Dukett on-site in a workshop at the Mission San Juan Capistrano. Photo: Troy Harvey
Late last summer a pair of swallows started building this nest on the mission grounds. Unfortunately, they didn’t finish, and no eggs were laid. Photo: Troy Harvey
Students from the Mission Basilica School dress in fanciful bird costumes and perform a traditional song and dance during the festival. Photo: Troy Harvey
Ornithologist Charles Brown, of the University of Tulsa, stands before the bells of the Mission San Juan Capistrano, which are rung during an official ceremony at the annual Festival of the Swallows. Photo: Troy Harvey
Visitors gather for the official bell ringing ceremony. Photo: Troy Harvey

If the project is a success, it will not only lead to the return of the festival’s main attraction, but will also be a small conservation boost for the birds. While Cliff Swallows are generally doing well throughout their breeding range—from Alaska to Central America—their numbers have declined in Southern California. Brown attributes the drop to landscape changes. “These are open-country birds for the most part,” he says. “Over the last 100 years, the growth of Eucalyptus trees and other woody plants have made this a much more forested area than it used to be.”

So far, mission employees have reported seeing swallows flitting about the property, though none have built nests yet. Brown isn’t discouraged. “Just because it doesn’t work this year doesn’t mean it might not happen next year, or the year after.”

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