Far fewer Vaux’s swifts return to Chapman Elementary this year [Video]

PORTLAND, Ore. — It’s a time-honored Portland tradition each September: grab a picnic basket and a few good friends and stake out a spot on the hill overlooking Chapman School in Northwest Portland, waiting for a spectacular show at sundown.

Thousands (usually) of tiny birds — Vaux’s swifts — dance through the sky, swirling around the school’s three-story-tall chimney, finally funneling inside to roost for the night. You’ll hear shouts from the crowd as the birds are spotted, oohs and ahhs as they approach the chimney, loud boos for the birds of prey that eat a few of them, and applause throughout the crowd of thousands after the final little bird tucks into the chimney for bed.

It’s a sight to behold, one you don’t want to miss if you’re in Portland in the fall, but if …