Dance of the swifts.

Byline: Whitney Malkin The Register-Guard

An impatient crowd grows restless as small, black darts begin to pepper the early evening sky.

One, then two, then one hundred.

The swifts have arrived.

Eyes peering skyward with rapt attention, the crowd inhales as the birds swirl above an aged chimney in South Eugene.

Small swirls become a steady ribbon as hundreds of birds, known as Vaux's swifts, weave around the towering smokestack of Agate Hall.

Diving like fighter pilots, they barrel toward the brick with determination, but at the last minute turn away and disperse. Exploding away from the chimney like fireworks, the corkscrew of movement fades as birds climb higher, scattering in a chaotic dance of noise and speed.

The crowd gathered at the base of the south university neighborhood waits in anticipation, held captive by 4 1/2 -inch birds whose black outlines stand out against a pale blue sky flushed by the hues of sunset.

Conversation quiets as the vortex of swifts hovers above. The question is on the minds of so many, gathered here with lawn chairs, that it almost seems audible: Will the birds make their nightly descent to roost in the Agate Hall smokestack? Or tonight, have they changed their minds?

Jean Miksch is certain the birds eventually will make their way down the chimney for the night, a spectacle that has drawn a crowd of almost 80 people to the parking lot on the edge of the University of Oregon campus on multiple nights this month.

"It's one of the best things you could ever see," she says with a wide grin. "I talk about it all the time, ever since I first saw it. It's really just an amazing feat of nature."

On Friday, Miksch had gathered a flock of seven followers, everyone from friends to her 10-year-old daughter, Emma, to watch the swifts make their descent.

"It's really, really cool," says Emma, pushing her glasses up onto the bridge of her nose to peer more intently at the darkening sky. A fifth-grader at River Road Elementary, she says her favorite part of the experience is when the birds finally make it into the chimney.

"They circle around and around," she says, demonstrating a circle with her fingers, "and then whoosh, they all go in at the same time."

The Miksches are not the only ones who have caught swift fever. For the past 30 years, Eugene residents have been gathering at the Agate Hall chimney, formerly the Condon School, to watch the cloud of swifts - which build to a peak of some 10,000 birds - make their descent.

By using the aging structure as their own personal brick hostel, the birds gain protection from hawks and warmth from the chilling fall air, says Dick Lamster, a former president of the Eugene Audubon Society.

The swifts roost in the chimney because their feet prohibit them from standing or walking - a trait that means they sleep in a fashion similar to bats - inside hollow trees, caves or, in some cases, chimneys.

Because they are unable to perch, the swifts eat, mate and drink while flying. They spend their few days in Eugene hunting insects along the Willamette River, but as night falls, return to the corner of 17th and Agate, where they sleep clinging to the walls with clawed feet.

The cigar-shaped birds' stay in Eugene can be as brief as a night, says Lamster, explaining that the swifts are headed south, migrating to warmer locales for the winter.

They'll return in the spring, an event that current Eugene Audubon Society President Maeve Sowles says marks a full circle of migration.

"We're sad to see them go," she says, "but they'll be back in the spring to breed and start all over again. It's a pretty amazing thing."

And on Friday, as the sun slips behind the rooftops in South Eugene, the first few eager Vaux's swifts flutter down the chimney, twittering as they make their way out of sight.

Held captive by the suspense, the crowd cheers as the rest of the birds began their downward spiral, falling like leaves blown in by a sharp wind.

Increasing in both number and speed, the Swifts begin to storm the smokestack, plummeting violently as if sucked by a cartoonish vacuum cleaner.

The crowd sighs as the last few birds flutter above the aged brick. Flapping their wings as if stretching, the remaining birds twitter and vanish, as if by magic.

Another night. Another journey. A lifetime of flight.

For those who want to see the evening spectacle, the swifts should remain in town at least through tonight.