Swifts in a Chimney

Last night we joined hundreds of other Portlanders at an event I would not have believed existed - and didn't, until we arrived. It took place at the Chapman Elementary school in the NW, and when we got there I was surprised to see so many people stretched out on a hill and across the playground, most with blankets and picnics and many with video cameras. In addition, there were several hundred children sliding down the hill on cardboard sleds. Everyone had parked on their chairs and blankets in line with the school's big, brick chimney - about 2 and a half stories tall and looking like it was built in the 1930's. Above the chimney swirled and flitted and swooshed and soared thousands, and thousands, of chimney swifts. (One Audubon website estimated 10,500 swifts last night and 1500 spectators!) Apparently this chimney is an annual stop on the birds' migration to Venezuela (or Argentina, depending on which overheard conversations you choose to believe). Each year, during the month of September, they begin swirling and diving above the chimney in droves and clouds just at dusk, before all diving into the chimney (in a surprisingly orderly fashion) to spend the night.

Needless to say, it was impressive. Also, turns out it is impressively difficult to estimate numbers of swirling birds (at least for us) and even though it looked very much as though there were birds continuously diving into the chimney throughout the entire hour we were there, it was nearly impossible to tell at any point whether there were now more or fewer birds left in the sky. Every ten minutes or so they would all form into one huge, circling cyclone of birds, all swooping clockwise around the chimney, with a steady stream appearing to drop off into the mouth of the column. Then something would cue them to split and spread out into a huge, billowing, entropic cloud of tiny spots, before forming another circling mass.

When it looked to our unaccustomed eyes like only 10% or so of the birds were left - which still resembled the largest flock of swallows I've ever seen - a peregrine falcon/Cooper's hawk (again, depends on who you overhear - I saw one kid run over to his mother and say "Mr. Morton says it's a peregrine falcon!") decided to come swooping in. On its first run through the cloud, it ended up being chased by a hundred or so swifts, which of course gained cheers and applause from the crowd. It circled out to nearly as far as one could see it, then came swooping back in, making unsuccessful dives at some of the 'teenage' swifts, out later than the rest of the pack. We didn't see it make any successful catches (good thing - I can imagine that might be somewhat distressing for a child who has come out to watch the swifts land) but it did ensure that the rest of the birds headed into the chimney. And that was it!

Despite the many words up there, I'm not sure I did the description justice. Here's a 30 second clip of the birds.