All during the month of September the Vaux’s swifts roost in the chimney at Chapman School, which is just a few blocks from my apartment. Mid-month I walked over to watch the flock aggregate and enter the chimney for the night and I can tell you it was pretty freakin’ amazing. This is the largest flock of Vaux’s swifts in the world, and they’ve been roosting in the chimney every year since the late 1980’s – in peak years, the flock was up to about 35,000 birds! Typically it’s around 15,000 – I’m not sure how many there were this year, but it seemed like a lot.
The swifts start circling the chimney about an hour before sunset and the flock grows bigger and bigger as individual birds join in. Just after sunset, all of a sudden, the birds start diving into the chimney all together – it takes a while for them to all get in there, and it is a prime opportunity for hawks to come swooping in for a meal. Apparently, the hawks will not only dive through the flock (which then scatters – it reminded me of the way a pool ripples when a stone is tossed into still water), but they’ll also sit on the edge of the chimney and even enter the chimney to grab birds. Interesting thing about the swifts too – they don’t perch – they cling to the inside of the chimney like a bat would. Anyway, here are some photos and a video for you to see what I’m talking about (the Portland Audubon Society also has some great information about the swifts here).