Every fall, during their annual southern migration, thousands of Vaux’s Swifts roost in an abandoned chimney at a school in Northwest Portland. They perform an intricate aerial dance at dusk, which lasts a little more than a half hour.
First, a small group of swifts–really, a dozen or so–appear and start circling in the sky. Then, magically, and a bit mysteriously, swifts start flying in from all directions, adding to a growing swarm. The swarm expands and contracts in diameter as it moves across the sky, always keeping the chimney in sight and range. After about 15 minutes or so, the swarm closes in on the chimney and a group of swifts peels off and spirals down inside. They then repeat the process a few times, with the group’s size gradually winnowing down.
The swifts’ dance by itself is cool enough to entertain multitudes of Portlanders through many September evenings, but, this being nature and all, you get added drama: hawks. Once the swarm builds to a critical mass, hawks will dive-bomb into it, trying to pull off a swift or two for dinner. Sometimes, a small group of swifts will break off and chase the hawk away, which is hilarious to see, and raises a cheer from the crowd on the ground. Sometimes, a hawk will get a swift, also to a rousing cheer. Then, at almost exactly the time it goes from dusk to dark, the last of the swifts dive into the chimney to a round of applause, and the audience packs up and heads off to their own roosting place.
It’s a lot of fun, and, if you live in Portland, it’s worth going to at least once in your life.