by Roger Clay, Wildlife Biologist
You hear some rustling noises coming from your chimney. Could it be Santa Claus? A quick check of your calendar says the day is June 15. Santa is probably not paying an early visit, but what you are likely hearing is the wing beat of a bird—the chimney swift.
There are about 80 species of swifts found throughout the globe except in the polar regions and on some oceanic islands. Swifts are truly aerial species. Making their living on the wing, these birds eat, drink, bathe, and gather nest materials while airborne.
The swifts belong to the bird family Apodidae (ah-POD-ih-dee) which means “without feet.” Of course the birds do have feet, but they are small and weak making perching and walking like most birds virtually impossible. Interestingly enough, hummingbirds are considered close relatives of the swifts and share small weak legs and feet.
Chimney swift is one of four swifts breeding in the United States, but is the only swift commonly found in the eastern U.S. Often described as a “cigar with wings,” the chimney swift is sooty gray overall with narrow curved wings. A body of about five inches terminates in a tail that is almost invisible giving the chimney swift its distinct “cigar” appearance.
As winter approaches and the availability of flying insects decreases, chimney swifts depart Alabama in October for South America. By mid-March the birds begin arriving back in Alabama to spend the spring and summer nesting.
The nesting habits of the chimney swift are perhaps the most interesting aspect of the species. The birds naturally nest in the darkened hollows of trees, but you would be hard pressed to find a chimney swift nesting in a tree these days. As their name implies, chimney swifts adapted to man’s presence and commonly nest on the inside walls of chimneys. But how do they build a nest on the side of a chimney?
Chimney swifts gather nesting material on the wing by breaking off dead twigs from the end of branches. Back at the chimney the bird attaches the twig to the wall with a sticky saliva that provides the glue to build its half cup shaped nest. In fact, bird nest soup is really the nest of a swift in Asia that builds its nest entirely of saliva!
Multiple chimney swifts may roost in the same chimney, but only one pair will nest in the structure. Usually four to five eggs are laid with both parents sharing incubation and the subsequent feeding of hatched young. Once nesting season is over and migration approaches, chimney swifts gather in flocks often making spectacular entrances into nighttime roosts with hundreds or thousands of birds funneling into suitable chimneys.
Today, chimney swifts may be hard-pressed to find suitable nest sites. Dead or dying trees are removed, tops of chimneys are screened, and new chimney construction makes nesting impossible. We aid other bird like the bluebird and purple martin by erecting nest structures and now there are plans available for a chimney swift nest structure.
If you have chimney swifts nesting in your chimney, it is a good idea to get your chimney cleaned periodically, since old nests may cause more of a fire in your chimney than you may want.