11 September 2020

In September chimney swifts (Chaetura pelagica) migrate through western Pennsylvania on their way to South America. Unlike songbirds, swifts migrate during the day but we often don’t see them because they travel so high. Birds of the World says they’ve been recorded above the clouds on the warm leading edge of a cold front, 7000 feet up!

At night swifts sleep in chimneys, choosing the most convenient place. The roost may hold more than 1000 birds per night though the individuals change as some leave for the south and others arrive from the north.

Since moving to Oakland in early August I now live within sight of the Cathedral Mansions chimney, one of the largest migratory roosts in the Pittsburgh area. When the weather’s fine I step out to watch them circle the chimney and dive into the roost. Last Sunday I invited Michelle Kienholz to join me. Her videos show some of what we witnessed.

We started watching while the sun was up but the swifts didn’t come close to the chimney until a few minutes after sunset. By that time it was obvious they were making very large circles around the chimney, flying out of our peripheral vision.

As the sky got darker the swifts circled closer and closer, faster and faster. To enter the chimney they stalled upright, then dove in. There were so many swifts they had to wait in line or circle out and try again.

We tried to count as they dove in but they were quick.

It was almost too dark to see when the last swift disappeared 20 minutes later.

My estimate was 1,500 chimney swifts.

Watch them live at the Audubon Society of Western Pennsylvania’s Virtual Chimney Swift Night Out, 25 September 2020, 7-9pm. Click here for details.

p.s. The swifts leave before dawn if the weather is good but this morning it’s overcast. A few swifts popped out of the chimney 15 minutes before dawn but all went back in.

UPDATE 18 SEPT 2020: I counted 1,300 chimney swifts tonight. The flock completed its dive into the chimney by 7:52pm.

(photo of three swifts by Jeff Davis; still shot and videos of Cathedral Mansions chimney swifts by Michelle Kienholz)