While St. Patrick's Day gets more attention, today, March 19th, is St. Joseph's Day. In observance of the feast day, it's customary to wear red. And today, the swallows return to Capistrano, a natural occurrence that takes place every year on March 19th.

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So, what is exactly is happening here? According to sanjuancapistrano.net/swallows:

"The miracle of the "Swallows" of Capistrano takes place each year at the Mission San Juan Capistano, on March 19th, St. Joseph's Day.

As the little birds wing their way back to the most famous Mission in California, the village of San Juan Capistrano takes on a fiesta air and the visitors from all parts of the world, and all walks of life, gather in great numbers to witness the "miracle" of the return of the swallows.

With the arrival of early dawn on St. Joseph's Day, the little birds begin to arrive and begin rebuilding their mud nests, which are clinging to the ruins of the old stone church of San Juan Capistrano.

After the summer spent within the sheltered walls of the Old Mission in San Juan Capistrano, the swallows take flight again, and on the Day of San Juan, October 23, they leave after circling the Mission bidding farewell to the "JEWEL OF ALL MISSIONS" San Juan Capistrano, California."