Where did the Chapman swifts go? They aren’t at the school, but the birds are still out there

The migrating Vaux's swifts, which normally roost by the thousands in the old chimney at Portland's Chapman Elementary School throughout September, have abandoned the site early this year.

Don't worry: The tiny birds have long used multiple sites to overnight in the area, and it seems many of them have taken up residence at new spots.

What remains a mystery is, why?

"It's unusual that they're not at Chapman," said Joe Liebezeit, assistant director of statewide conservation for the Bird Alliance of Oregon . "They've been using that chimney in large numbers since the 1980s, and I think we get into the habit of relying on that."

It's not that unusual for birds to forgo using a chimney for several years, only to return sometime later. What is strange is for the swifts to abandon their largest, most consistent roosting spot in the city.

"Anytime you see birds disappearing from a place that they've relied on for many, many years in such large numbers, it definitely is a cause for concern from the conservation end," Liebezeit said.

In past years, the decommissioned Chapman school chimney has drawn more than 10,000 swifts each night as the birds make their migration south in September and early October. This year, the peak number of estimated swifts was 5,430 birds counted on Sept. 2.

But by Sept. 14, the swifts had abandoned the Chapman chimney, and they haven't been back since.

After the migration season, the Bird Alliance of Oregon will investigate the Chapman chimney to make sure there isn't an internal blockage that's keeping the swifts away.

Liebezeit suspects an increase in predators may have scared the birds away. Cooper's hawks and peregrine falcons, which often catch swifts as they enter the chimney, seem to be staying at Chapman for longer periods of time.

"I monitored the swifts on Aug. 31 this year," Liebezeit said, "and there was a Cooper's hawk that flew to the top of the chimney and hung out there for 45 minutes, into when the sun was down, and the birds were still waiting to go in."

The Bird Alliance doesn't think the presence of people at the school caused the swifts to leave. In addition to counting numbers of birds, the nonprofit also counts the number of people watching them each night. While an errant drone has scared the flocks away in the past, spectators on the ground have not.

So, if the swifts aren't at Chapman, where are they?

Lately, about 4,000 swifts have been spotted roosting nightly at the Holy Trinity Greek Orthodox Church at Northeast Glisan Street and 32nd Avenue. The Bird Alliance of Oregon has been in touch with church staff to ensure the furnace isn't used while the birds are roosting, Liebezeit said.

He also cautioned bird watchers about overrunning the new location, which isn't equipped to handle the thousands of onlookers that have traditionally watched the birds at Chapman school.

"A sudden influx of the public to different neighborhoods can cause disruptions in parking, an increase in trash, and potentially inhibit local events and businesses," the alliance wrote in an online update about the swifts. "We want to ensure that any new-found fame of a neighborhood or institution based on their avian guests doesn't cause increased challenges."

Larry Schwitters, who runs the swift tracking site Vaux's Happening , has a theory about why the birds have moved away from Chapman. Schwitters tracks reports of swift sightings all along the west coast. Over the past few years, the birds also stopped roosting near Joint Base Lewis-McChord in Washington.

"It began about the time the wee birds discovered the just opened stack in Rainier," he wrote in an email. "They now push on from Canada to Rainier for their first overnighter in the USA."

That "stack" is the Riverside Community Church in Rainier . Since 2019, after a cover was removed from the church's decommissioned chimney, it's become one of the largest tracked roosting sites in Oregon. As recently as last week, volunteers were counting more than 15,000 swifts a night there. It's possible the birds are stopping in Rainier and then bypassing Portland. About 10,000 swifts were also counted last week at Agate Hall in Eugene.

In more promising news, Schwitters has gotten reports of thousands of swifts roosting in what was their original habitat: a hollowed out old growth tree in the Olympic National Park near Lake Cushman. That tree hadn't previously been tracked by Vaux's Happening.

Volunteers with the Bird Alliance of Oregon will continue to monitor the Chapman chimney through the end of the month, as they do every year.

"It might be a little boring for them if there's no birds that show up, but negative data is just as important as getting count data," Liebezeit said. "Chapman's always been a stalwart site where we've had many, many birds every year for decades. Things have changed, at least this year. We'll see what happens next year."