For three weeks this month, thousands of Vaux's and hundreds of humans gather each night at the school. The people find a place to sit and watch the aerial show; the birds show up around dusk to swirl around and around before abruptly pouring themselves like a reverse spill of pepper into their container. Wanna see? Here's a video taken in 2009.
The birds are on their annual migration to Central America and Venezuela. They used to hang out in old hollowed-out trees, but those are in short supply these days, so the birds make do with chimneys along the western edge of North America.
When I was at Chapman recently, a peregrine falcon also made an appearance, looking for a quick takeout meal. The falcon swooped into the midst of the birds, but the swifts rallied and mobbed it, chasing it off into the distance--to the enthusiastic applause of the watching crowd. The swifts returned and went back to swirling around the chimney--when, out of nowhere, the falcon appeared again, tucked its wings tight and zoomed into their midst. It nailed a swift and made off with it--ignoring the collective gasp from the appalled humans below.
I understand that sometimes when a peregrine or Cooper's hawk shows up, the crowd boos. Ya gotta love Portland.