Environmental Almanac

An appreciation for chimney swifts

On the wing from dawn to dusk, chimney swifts are among the most aerial of birds and the essence of summer in the Midwest.
Sketch of chimney swifts from a 1913 publication for teachers in New York giving them material for "nature study."

This sketch of chimney swifts comes from a 1913 publication for teachers in New York giving them material for "nature study." n.a.

If you’re a bird, and you want lots of attention from humans, your best bets are a dramatic color scheme, or a loud, pretty song.  Combine these characteristics, as the northern cardinal does, and you wind up as the state bird, and you get sports teams named after you.  Without them, you wind up as popular as, well, the chimney swift. For me, though, these gregarious birds are part of the essence of summer, and their disappearance from our skies in mid October is the surest sign that late summer has given way to early fall.

One of the great things about observing chimney swifts is that most people can see them simply by stepping outside and looking up.  They’re on the wing from dawn to dusk, although they’re most easily seen in the evening sky.  This is especially true as they gather in flocks of hundreds for the journey to their winter range in South America.  Perhaps you have seen one of these flocks circling a large chimney late in the evening, with birds dropping in by ones and twos as they settle in to roost for the night.

You can distinguish chimney swifts from the other dark birds commonly seen overhead by their shape and the patterns of their flight.  They are small, stubby creatures—dubbed “flying cigars” by some —with sickle-shaped, backward arcing wings.  Their flight is best described as careening.  They beat their wings rapidly, bank sharply, glide, dive, and soar, all in very quick succession, twittering amiably as they go.

In fact, chimney swifts are known to ornithologists as the most aerial of eastern land birds.  They feed while flying, catching insects and ballooning spiders.  They drink while flying by skimming the surface of a body of water with mouth open.  They collect nesting material while flying, snapping off twigs from trees as they go by.  Indeed, chimney swifts even do their courting and mating on the wing. 

That swifts live so much of their lives in the air is not simply a matter of preference.  Their small but strong feet are designed for clinging to vertical surfaces—such as the chimneys where they so often nest and roost—and do not allow them to perch or stand upright the way songbirds do.

Before chimney-building humans came to dominate the landscape of the eastern United States, chimney swifts favored large hollow trees for nesting and roosting.  And having adapted to the use of chimneys they expanded their range significantly over the course of the 20th century.  Whereas prior to the 1940s they were rare west of the Mississippi, they are now found from the east coast to the foot of the Rocky Mountains.

Despite the expansion of their range, however, chimney swift numbers have declined considerably since the 1960s, and the decline has accelerated in recent years, especially in select parts of their range. 

According to Maureen Hurd, who is studying chimney swifts as she pursues a Master’s degree at the U of I, there are likely a number of causes involved. Chief among these are loss of habitat as old chimneys are capped or torn down and changes in the populations of the insects on which they feed. Along those lines, she also pointed out that other birds that feed by capturing insects in flight, such as common nighthawks, are also declining in number.

While I recognize the importance of sorting through those questions in the long term, for now I’m just glad we’ve got a few more weeks to enjoy chimney swifts overhead before they leave for the winter.

Some chimneys to check

At chimneys where large flocks spend the night during fall migration, chimney swifts create a minor spectacle each evening as they gather and fly in a spiral together before dropping in. This lasts about a half hour just as the sky goes from light to dark, from sunset and after.

Among the places you might check for this in east central Illinois are the Head Start building on Old Church Road in Savoy, the Saint Joseph-Ogden High School, University Place Christian Church on Wright Street (just north of Springfield Ave.), Westview School in Champaign, and the Landmark Hotel in Urbana.

Chimney swifts dropping in to roost for the night.