City Cast

What's the Deal with Portland's Swarming Swifts?

Rachel Monahan
Posted on September 7
dark birds above a blond brick chimney

Vaux's swifts swirling into the chimney at Chapman Elementary School, in Portland, Ore. (Sam May)

You know it’s September in Portland when 3,000 people, many of whom don’t ordinarily “put a bird” on their evening, go out to watch Vaux’s swifts at sunset.

The birds pass through Portland on their migration south and, each night in September, swarm like a tornado and then dive into an old chimney at Chapman Elementary School in Northwest. That’s where they spend the night huddled together.

(It’s also a heart-warming display of Portland’s nature lovers. My favorite moment last year was discovering a Portlander who’d brought their pet bird to watch the swifts.)

Today here are some intriguing facts (and mysteries) about the Vaux’s swifts:

  • The Chapman spot is, if not the biggest chimney the birds stop at along their migratory path, then one of the biggest. “There can be as many as 15 or 16,000 birds, on any single given night in the fall, that use the chimney,” says Joe Liebezeit, Portland Audubon’s assistant director of statewide conservation. “It could definitely impact their population and they'd have to find other places to roost” if the chimney were ever taken down.
  • The birds breed in the Pacific Northwest then travel into Central America for the winter.
  • Scientists don’t know why the swifts pick some chimneys and not others or why the Chapman chimney has remained the Portland stop on their migration south. There are some chimneys of similar size not far away, but they haven’t been used by as many birds or as consistently.
  • Why don’t other species need the spot? Many songbirds eat during the day and migrate at night. These swifts can eat as they travel. But at night they need to keep warm so they huddle together in the chimney. They also cluster together to stay out of the reaches of predators.
  • It’s also unknown which bird leads the flock. It’s not clear how they decide to start entering the chimney or who the decider is. But the U.S. military is interested in studying their movements. “There was a guy in the U.S. Army, who had gotten a grant to look at murmurations,” says Liebezeit. “There's development of drones is what I'm saying, for military purposes.”
sunset-colored sky with a swarm of black birds

Black birds swarm against the sunset-colored sky. (Devlyn)


Every night this month (or until the swifts are gone). Arrive an hour before sunset.  It’s better viewing and more pleasant when the weather is dry. Which it’s supposed to be for the coming week.

The number of swifts usually peaks mid-September, but you may want to visit in the next week as the swifts this year started arriving a little early. (But it’s difficult for experts to predict the peaks.)


Chapman Elementary, specifically on the southwest side of the school.

Pro Tips

  • Bring a blanket and even a picnic dinner.
  • Bring your own cardboard to entertain the young (or the young-at-heart) with grass sledding as well.
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