Image from Marinarena's travel page.
Today is the feast day of San Juan, the day that the swallows of San Juan Capistrano leave the mission on their 7,500 mile, month-long migration to Goya, Argentina for the winter.
The bands of swallows fueling for flight are calorie vaccuums, consuming up to 1,000 insects daily and providing an enormous insecticidal fleet. At dawn of February 18th next year, they will leave Goya, returning en masse to Capistrano on March 19th as they do annually and have since the Cenozoic Age, a couple of million years ago.
Read here about the sister cities and about the amazing travel of the swallows from an Argentine scientist. I love cyclically recurrent natural spectacles like this one, and hope someday to see it in person.
However, if you're looking for something more emblematic of the thinning of the veil between the material and spirit worlds at this time of year, you can still just make Carlsbad- this I've seen- and witness the pre-migratory flapping of hundreds of thousands of free-tail bats.