Chimney Swifts over Downtowns

Nature Notes for August 19, 2011

You’ve probably heard them as you go about your business in downtown Port Hope or Cobourg in the summer. Chimney Swifts chattering overhead are a welcome sign of summer. They are still around, though, foraging for insects on the wing.

The Peterson field guide describes them as being shaped like “a cigar with wings” and most subsequent field guide authors have quoted this description. They are small, dark oblong-shaped birds with long curved wings. Their flight style is quite distinctive, since they fly with stiff, fluttery wing beats.

Although they superficially resemble swallows, and are often found foraging with swallows, their closest relative is thought to be the hummingbird. They spend most of their time in flight where they feed on flying insects and a few ballooning spiders.

Chimney Swifts often nest in chimneys, hence their name. Before buildings were available, they nested in hollow trees or caves.

Their nests are a small, rather flimsy, flat saucer of twigs glued together and to the supporting vertical surface with swift saliva. The birds collect the uniform sized twigs in flight.

The nests of an Asian species of swift are prized as the main ingredient of birds nest soup. This very expensive soup is really just cooked swift saliva!

Swifts have very short, weak legs. Their toes are specially adapted for clinging onto vertical surfaces and the edge of their nests. As well, they have stiff projections from their tail feathers which aid in keeping balanced when they perch.

As with all aerial foragers, Chimney Swift populations showed a definite population decline between Ontario’s two Breeding Bird Atlases. As with many other species, this decline is thought to be due to habitat loss.

However, some Chimney Swift habitat loss has to do with modifications to human built chimneys. Many chimneys built in the nineteenth century are no longer in use and many have been taken down or closed off. Changing fire codes require metal chimney liners. Many chimneys are capped to prevent access to animals and birds which humans consider pests.

In some places, artificial structures are being erected to provide Chimney Swifts with suitable nest sites. Two have been erected in Ferris Provincial Park in Campbellford.

As a bird bander, I have had the opportunity to view many species of small birds up close. However, my one close encounter with Chimney Swifts was in a decidedly non-naturalist setting. On September 4, 2002, Northumberland Players held a reception at the Firehall in Cobourg to publicize the upcoming season. At that time, the Firehall was not air conditioned. It was a warm evening, so all the windows were open. Suddenly into the midst of the wine and cheese reception flew two Chimney Swifts. They were a bit confused and crashed into the wall opposite the open windows.

Most of those present thought that they were bats and became a bit hysterical. I leapt into the fray, picked up the frightened birds and carried them downstairs to the parking lot. One flew off immediately. The other one needed a bit of time to recover its senses, but after a few minutes, it, too, recovered and flew off to join the other swifts swirling around Victoria Hall.

Chimney Swifts have started to migrate and most will be gone in about a month. Most winter in South America, in Peru and western Brazil.