EUGENE, Ore. — There’s a natural phenomenon happening at a building near the University of Oregon right now, and it’s native to Eugene.
When the sun sets on the university in late September, there’s a unique buzz across the street from Hayward Field at Agate Hall. The students aren’t here yet, but something else is settling in.
The university doesn’t use the chimney attached to Agate Hall anymore, but they keep it around for thousands of birds that use it only a couple times a year, as they migrate south for the winter.
“Some can come as far as southern Alaska and British Columbia,” said naturalist Rick Ahrens.
Local residents gather at Agate Hall, perched in the parking lot waiting to greet their guests who’ve come so far.
“A friend told me about it and I had to come see it for myself,” said Eugene resident Dahlia Garza.
But this isn’t your typical bird watching. These onlookers are eyeing the old chimney, which is serving as a temporary channel for the phenomenon that only happens in Eugene twice a year.
“There could be as many as 5,000 or 6,000 over the last week going down the chimney and we’ve had high of 12,000 or more,” Ahrens said.
Thousands of birds will funnel into the old chimney when the time is right, usually 10 to 30 minutes minutes before sunset. They are called Vaux’s Swift, and you won’t see these species resting on trees or landing on ledges.
“A lot of birds can sit on a tree and perch to sleep all night, but these can’t. They have four toes forward, so they have to hang,” Ahrens said.
Ahrens says these birds use chimneys because they resemble snags or old hallowed out trees–a space Ahrens says is now limited.
“There’s 30, maybe at least 50 chimneys between San Diego to British Columbia that these birds use migrating north in the spring and south in the fall,” Ahrens said.
Swooping into these chimneys has its challenges. Swifts attract predators such as a nearby small forest hawk, who is ready for an evening snack. The birds try to distract their enemy by moving in unison together.
“It’s difficult for a predator to pick out a single bird,” Ahrens said.
But it doesn’t always prove successful for every swift.
Now that the chimney is clear and the sun has set, the birds are ready to make their move and swarm in for the night’s slumber.
“Aesthetically it’s really beautiful and ecologically…these birds eat a lot of insects each birds will eat hundreds of insects. They really provide free services to us,” Ahrens said.
It’s a free service and an seasonal spectacle right in our own backyard.
The birds are expected to still be using this chimney nightly for the next few weeks. The Lane County Audubon is hosting an information table event Sept. 20 and 27 for people who want to come check it out. The swifts’ behavior is different every night, so weather permitting the sight can always be different.