The Vaux’s Swift is a tiny bird – some people call it “a cigar with wings.” But every fall these little birds make a big trip, from summer breeding grounds in the Pacific Northwest down to their winter home in Central and South America. Along the way, many of them roost as a big flock in chimneys up and down the west coast. And their murmurations in the air – and simultaneously dive together into chimneys – are so spectacular that they draw crowds.

There have been watch parties in Los Angeles, and Eugene – and in Portland the past couple weeks, crowds turned out night after night to see these little birds go to bed. It’s part of an annual tradition known locally as “Swift Watch.”

A bird that doesn’t perch

Spectators see the first sighting of Vaux’s swifts for the evening at Chapman Elementary in Portland, Oregon on September 8, 2024.

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Vaux’s swifts are about the size of a sparrow, but their closest relatives are actually hummingbirds.

“They’re so aerodynamic, and they have these swept-back wings — kind of like these fancy military jets,” says Joe Leibezeit, the assistant conservation director at Bird Alliance of Oregon.

These sleek birds do everything on the wing — eating, drinking, even mating. And, says Liebezeit, they’ve adapted to staying in the air. They’re not known to walk, hop or perch on a branch. “They’re a different kind of bird than a perching bird,” explains Liebezeit. “They don’t have the same muscle structure to do what a songbird does, to securely land on the branch and grab onto it.”

The only time they stop flying is at night when they roost. During the summer, swifts sleep in their own nests in small, residential chimneys, or the occasional hollow tree. But during the fall migration they form flocks of thousands, and huddle up in bigger smokestacks to share body heat.

Crowds gather to see migrating Vaux’s swifts roosting in the chimney at Chapman Elementary in Portland, Oregon.

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Georgiana Cassell’s Vaux’s Swifts memorabilia in Portland, Oregon.

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While their sharp little toes aren’t great for wrapping around a branch, they’re perfect for clinging to the rough stone of a chimney. And they have even developed little barbs on their short, stubby tails to help. “Kind of like a tripod,” laughs Liebezeit.

Chain of chimneys

Historically as they migrated, Vaux’s Swifts would roost in hollow trees. But Larry Schwitters – a retired science teacher who runs a website called Vaux Happening – says they have come to prefer chimneys, because the masonry soaks up the heat of the day.

“The swifts are not good at insulating themselves,” explains Schwitters. “So they press themselves against the bricks that are releasing heat. And it can be as much as 25 degrees warmer inside a chimney.”

On the Vaux Happening website, Schwitters gathers swift counts from bird groups and citizen scientists up and down the west coast. All together, it’s tens of thousands of birds, roosting at about a dozen major sites, about a day’s flight apart.

The Bird Alliance of Oregon has a volunteer information table at Chapman Elementary for visitors coming to watch Vaux’s swifts roosting in Portland, Oregon.

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Hester Van Heemstra watches Vaux’s swifts swirl in the sky at Chapman Elementary in Portland, Oregon.

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Once the swifts get to a site, they’ll stay and feed for a day or two before moving on to the next one, says Joe Liebezeit.

“They’re gathering energy, they’re gathering fat stores on their body because they have to migrate hundreds of miles to the next stopover point.”

Although humans have provided these cozy brick hotels for the swifts, it hasn’t always been a seamless relationship. Some of the old smokestacks have been torn down because of development. Some old chimneys have been capped, because people don’t want to deal with the birds (or their poop). And newer chimneys have metal liners, which the birds can’t cling to.

Flocks of birds, flocks of people

The birds’ murmuration in the air, and simultaneous dive into the chimney, attracts onlookers every year in Portland, Oregon.

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In Portland, a chimney at Chapman Elementary School has hosted a flock of swifts since the 1980s. The Portland swift count tends to peak in mid-September – this year, the first birds were counted August 26th, and the most birds were counted September 2nd (over 5,000).

When it’s swift time, Portlanders grab picnic blankets and lawn chairs, and stake out swift-watching sites on the lawn surrounding the school. Groups share takeout and potluck picnics, while kids slide down the hill on sheets of cardboard.

The tradition is known in Portland as “Swift Watch,” and people turn out for days on end with friends, food, and pets to cheer on the birds.

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“This is a very Portland thing, that there’s hundreds of people gathered on a school lawn to watch birds fly into a chimney,” jokes Jeremy Lui, as he settles in to watch. (That night Bird Alliance of Oregon counted 1,500 people there.)

About an hour before sunset, the birds begin to gather in the sky, and the crowd gasps and claps as the formation swirls around.

Suzi Asmus, who is out celebrating her birthday, says “I love when everybody starts oohing and aahing together – it just feels like a community event.”

Asmus is one of five people out celebrating a birthday on this particular September night. But really, everyone seems to be having a party. People are running into friends, sharing pizza with strangers, complimenting dogs and babies.

Georgiana Cassell drove down from Seattle with friends to watch Vaux’s Swifts roosting at Chapman Elementary in Portland, Oregon.

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Kids slide down a grassy hill on scraps of cardboard while waiting for the Vaux’s Swifts to gather at sunset in Portland, Oregon.

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“The vibes, the family-centricness of it all is really sweet,” says Dylan Winkler. “That people just come and sit on a hill for hours to watch birds is so wholesome.”

But this wholesome night is not without its drama. At one point, a juvenile Cooper’s Hawk flies up to perch on the chimney, aiming to pick off a meal from the flock. The crowd collectively boos as the hawk grabs his prey. Cameron Trost, a volunteer with Bird Alliance of Oregon, isn’t one of them. He says the hawk “is indigenous to the area, so we support his efforts.”

A short time after sunset, the flock’s circles start dipping closer and closer to the chimney, their loose swirl starts to funnel, and the excitement of the crowd picks up. The amount of time it takes for the swifts to actually enter the chimney can vary – depending on the size of the flock, whether they’re interrupted by a hawk, and if they do it all in one pass. But on this night, the flock of about two thousand birds pours into the chimney continuously in the space of about a minute. It’s like a magic trick. And the crowd cheers.

At sunset, Portlanders watch migrating Vaux’s swifts as they prepare to roost in the Chapman Elementary chimney in Portland, Oregon.

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According to Vaux Happening, tens of thousands of birds roost at about a dozen major sites up and down the west coast, about a day’s flight apart.

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“It’s a great connection between people all gathered together on a lawn,” says Joe Liebezeit, “and then this flock of birds that are all kind of in synchronicity, flying in a murmuration… And it’s a cool connection between two species.”