Portland's Vaux's Swifts leave Chapman Elementary early in 'unusual' phenomenon

PORTLAND, Ore. (KOIN) – Watching Vaux’s Swifts roost in the chimney of Chapman Elementary School has been a Portland tradition for decades.

But this year, the Bird Alliance of Oregon, a wildlife advocacy organization, noticed something "unusual": a significant decrease in the number of Swifts at Chapman in the last week, with the count dropping to almost zero.

“This phenomena of them not being at Chapman is unusual in the sense that we’ve had them there for years, for decades really, and in big numbers every year and I’ve never seen them absent,” said Joe Liebezeit, assistant director of statewide conservation for the Bird Alliance of Oregon.

The Bird Alliance of Oregon has been monitoring the swifts at Chapman and other chimneys in the area for the last 15 years with help from trained community members who count the birds every night during the fall migration from late August until early October.

Typically, Chapman sees the number of swifts grow from the hundreds to thousands in early September before growing to as many as 15,000 swifts in the chimney on any given night before they leave for fall migration, Liebezeit explained.

This year, the Bird Alliance reported a peak of 5,430 swifts at Chapman on Sept. 2.

“This year is very unusual. We were expecting our peak bird numbers to be five, six, or even [thousands more] in mid-September,” Liebezeit said. “But there’s no swifts there at this point right now or not that we know of.”

Some community members on social media have speculated that the large crowds of swift watchers may have driven the birds away; however, Liebezeit said that's likely not the case.

"Every year, as we monitor the swifts, we also monitor how many people show up," he said. "For many years, there's been thousands of people showing up to look at the swifts, so I don't think people on the ground is having any impact on the swifts using the chimney at Chapman."

Northwest Portland’s Chapman Elementary isn’t the only roost site for swifts in the area, but it is the largest of the sites.

This year, it appears the swifts have moved to other chimneys, the Bird Alliance said.

While the organization cannot definitively say why the swifts left early, they do have one theory that predators may be to blame.

“There are predators like peregrine falcons and Cooper’s hawks that on many nights during the fall migration, will come and visit the Chapman chimney and sometimes prey on one or two of the swifts that are there,” Liebezeit explained. “That’s been happening every year that we’ve been doing this monitoring. It’s a natural occurrence.”

“We’re concerned that maybe this year, the presence of predators is for a longer duration, but we need to look at the data. We are collecting data as our counters count the birds that go into the chimney. We also monitor predator behavior, so that’s one thing we have to look at more closely and see if that’s a factor,” he added.

“We do know that the swifts seem to be moving to other places. We don’t know for sure if it’s the exact swifts that would be normally using Chapman, because we don’t have them individually marked, but we do know that as the number at Chapman has decreased, there’s another chimney or two in the Portland metro area that the numbers have increased,” Liebezeit said.

“It might be a little boring for our volunteers at this point but if we’re not there documenting what’s going on, we won’t know if they come back because we can’t really predict what’s going on in the minds of these little birds. So, maybe tonight, they’ll decide to go back to Chapman. We just have no idea," he furthered.

From a conservation standpoint, Liebezeit said there's always concern for swifts because their population is in decline, noting the alliance is hopeful because it appears the birds may be moving to another area nearby.

“On the other aspect, though, in terms of the community's engagement on the Swifts, it is a bit disappointing, because it's such a great way when people come to Chapman to really enjoy this spectacle of wildlife in an urban setting, and people have gotten accustomed to it and used to it, and it's such a celebratory thing, we hope that returns. But in the future, if it doesn't return, there might be other places in Portland where we can help create that same kind of connection between this wildlife spectacle and people enjoying that," Liebezeit said.