Portland has no shortage of awe-inspiring sights: a snow-capped Mount Hood breaking from the clouds. Waterfront Park’s cherry trees bursting into fluffy bloom. A mile-long parade of naked cyclists. But when it comes to sheer natural showmanship, nothing can match the spectacle that unfolds every September at Northwest Portland’s Chapman Elementary School, when the building’s decommissioned chimney becomes a roosting site for migrating Vaux’s swifts. Each evening, thousands of tiny birds gather into a whirling funnel and nosedive to their beds, like a living plume of smoke. It’s an indisputable marvel.

Just as remarkable as the avian phenomenon is the human one: these teeny aerialists bring out thousands of fans, who for a few weeks transform a sun-bleached hillside next to an elementary school into the place to be. Picnic blankets crowd the knoll. Friends laugh. Teenagers canoodle. Parents eat cheese and sip wine as their children run feral, flinging themselves down the steep slope on flattened sheets of cardboard. Then, just before twilight, as the birds begin their descent, all attention turns to the darkening cloud. A hush falls. We’re all swifties now.

Perhaps you’re a Portland lifer who makes an annual pilgrimage to Chapman. Maybe you moved here last week (welcome!). Regardless, here’s what you need to know about our city’s favorite temporary resident.

What are these birds doing?

In late summer, Vaux’s swifts—wee things, just four to five inches long and resembling “cigars with wings”—flock nightly in huge groups. It’s part of their preparation for their southward migration to Central America, and since the late 1980s, they’ve made the Chapman chimney one of their roosts. While numbers upwards of 35,000 have been recorded, high counts in recent years tend more toward 10,000. Bird Alliance of Oregon volunteers are out most evenings, weather and air quality permitting, to take tallies and answer questions. They’ve got a few taxidermied specimens, too, if you’d like to see one of these cuties up close.

Where does it happen?

At Chapman Elementary School in Northwest Portland, near Forest Park. Head to the hillside above the soccer fields, along NW Pettygrove Street. Parking in the neighborhood is scarce, so consider carpooling, riding your bike, or taking transit.

When does it happen?

The swifts usually start arriving in late August and are generally gone by early October. Numbers peak during the second and third weeks of September. (You can follow along with the nightly tallies, which in 2024 began on August 26.) While in Portland, the birds spend their days on the wing, feasting on flying insects, and show up at the school as dusk approaches. Aim to arrive at least an hour before sunset; on nice evenings, the masses may turn up well before then, claiming flatter spots at the top of the hill. According to the Bird Alliance, average attendance last year was 900, with some nights exceeding 3,000.

What should I bring?

A picnic blanket or chair, snacks, and—if you’re a kid—a piece of cardboard for careening down the hill. Bring binoculars if you have them, or borrow a pair from a Bird Alliance volunteer.

This sounds way too wholesome.

Is it drama you’re after? Say hello to the circling Cooper’s hawks. The crow-size raptors, along with the occasional peregrine falcon, love to snatch a swift for supper, and their arrival elicits gasps and jeers from the crowd.

What goes in must come out, right? What happens in the morning?

Unless it’s rainy, in which case they might hunker all day, swifts exit their roost sometime after sunrise, once the insects they eat have become active. They emerge like popcorn spilling over the edge of the pot, bursting over the lip of the chimney and swooping gently down before flitting off. No dramatic funnel cloud here, alas, but the human crowds are almost certainly more manageable. (If you’re seeking a little more action, this could also be your chance to witness predation by crows.)

Can I see swifts anywhere else?

A handful of other metro-area chimneys host swifts, including the old high school in Oregon City (now home to the Clackamas Academy of Industrial Sciences), but these sites can be inconsistent. Last year, swifts returned after a years-long absence to Mackin’s Auto Body in Kenton, with hundreds of birds appearing nightly.

While Chapman sees some of the largest groups of swifts along the Pacific Flyway, those seeking even larger flocks can travel 50 miles north to the Columbia County town of Rainier. Last year, Chapman’s highest nightly count was 11,440. At Rainier’s Riverside Community Church, meanwhile? 20,000.