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Chimney Swift

Chaetura pelagica

 

Introduction


An excited twittering fills the air. You look up and see birds flying with stiff wings like a boomerang and bodies shaped like cigars. They swoop and glide through the air, their graceful flight and active calls giving the impression of a party above the rooftops. The party lasts all summer. 


Description


Chimney swifts are about five inches long and fly on long, pointy wings that they flap somewhat stiffly to gain a little speed or height. Then they swoop and glide to catch their insect prey. They have tiny feet that are only useful for clinging to vertical surfaces. Chimney swifts cannot stand or move about on flat ground. Aside from nesting and roosting (resting for the night) chimney swifts stay airborne. 


Diet


Chimney swifts eat insects that they catch out of the air. 


Behavior 


As you might guess from their name, chimney swifts are closely associated with buildings, in particular interior, vertical surfaces. Chimneys fit the bill, as might rooms in broken down, abandoned buildings. 


They build nests out of sticks glued onto a vertical surface with their saliva. They raise one or two broods of three to five young, whose high-pitched, raspy calls can sometimes annoy homeowners. 


Chimney swifts are champion migrators. They spend their winters in northern South America and return to Philadelphia towards the end of April. As fall approaches and it is time to fly south again, chimney swifts form large flocks that roost together in bigger chimneys, hundreds to thousands of swifts end the day by flying down into the chimney like a brief vortex of birds draining down into the structure.


History with Humans


Before there were chimneys in North America, chimney swifts nested and roosted in large hollow trees. European colonization resulted in widespread deforestation, which eliminated the large hollow trees while replacing them with stone and brick chimneys. The swifts adapted to the new structures. 


Observing Chimney Swifts


Chimney swifts are extremely easy to observe throughout the city from late spring to early fall. They always seem to be chattering to each other, which gives you the signal to look up and find them flying above. They are particularly easy to find in the morning and later afternoon, as well as when a coming storm roils the summer skies with moist, heavy wind. 


Keep a close eye on chimney swifts in the summer and you can spot them flying back to their nest chimneys. Watch as they take an awkward turn down to drop in to feed their young. In the fall look for chimney swifts roosting in places like large chimneys at school buildings or churches. At dusk you can watch hundreds or thousands of birds tuck in for the night, one of our city’s most dramatic wildlife events.


Living with Chimney Swifts


Like many birds that eat insects, chimney swift populations have been declining. You can help support chimney swifts, along with bats, swallows, spiders, and many other bug-eating critters, by cutting back on insecticide use. Get rid of your bug zapper too. They do not do a good job of killing mosquitoes. Instead they mostly kill insects that cause no problems for humans but are great food for our insectivorous neighbors.


More Resources


Check out BirdPhilly.org for more about birding in Philadelphia. You can find a birding walk near you and get tips and guidance from experienced local birders. You can learn more about chimney swifts at All About Birds


For more on how you can help birds in general, here are seven actions you can take to help birds.

 

An excited twittering fills the sky as dusk approaches. Watch chimney swifts from Billy's roofs and learn about one of our must urban native birds. Thanks to our partners at Grid Magazine for producing the video and to the William Penn Foundation for their support.