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© Copyright 1999, Jim Loy
Everyone (almost) knows that the swallows fly back to San Juan Capistrano (in California), on the first day of spring. The Vernal (spring) Equinox varies from Mar. 20 to Mar. 21. So, in 1999, Mar. 19, no swallows, Mar. 20 (spring), more swallows than you can shake a stick at (illegal in Capistrano?), right? It is a miracle.
Wait a minute. The original legend is that they show up on Mar. 19, St. Joseph's Day. So, they've been there a whole day before those tourists arrived to see them. It looks like those swallows use the Gregorian Calendar (as we do), by the way. They wouldn't get there on the 18th, would they?
It turns out that the swallows arrive any time they feel like it. But, mostly, they arrive somewhat near the first day of spring. It mainly depends on the weather, and the food supply. They may have been there for weeks.