“The annual swallow migration has received a lot of attention over the years. For instance, Leon Rene’s 1939 hit, When the Swallows Come Back to Capistrano song lyrics are a tribute to the long migration.
“The amazing journey takes the swallows over 12,000 miles round-trip. They abandon their winter haven in Goya, Corrientes, Argentina and travel to southern California, arriving on St Joseph’s Day (March 19th)…”
Excerpt from http://www.arkanimals.com/capistrano-swallows/ .