Center for Conservation Biology

Basically nondescript, it is easy to understand why chimney swifts are likened to flying cigars. They are dark brown above and below, with slightly lighter breast and throat. Their wings are long and angular for their torpedo-shaped bodies making them extremely quick and agile in flight. Insectivorous, they spend most of their waking lives on the wing, alternating between rapid wing beats and short glides. Chimney swifts spend much of the time foraging at high altitudes, unlike most swallows, and so go unseen for much of the time. Only the sound of their twittering call notes draws attention to them.

Chimney swifts are adapted to life on vertical surfaces. They have 4 toes forward to aid in clinging, and their tail has feather shafts that extend beyond the vanes to anchor them in place while perched. Their tiny feet are ill suited to supporting their bodies on horizontal substrates. In order to nest successfully along vertical walls, chimney swifts have a natural adhesive. They lace together small twigs and secure them to the wall with their glue-like saliva. The final structure is an unlined, brittle, half-saucer of a nest rigidly anchored to the wall once the saliva dries. In it they lay 4 to 6 white eggs. Incubation lasts 19-21 days, with the young fledging in another 28-30 days. Fledging is a perilous time for young swifts in chimneys, and accounts for much of their first year mortality. Once past these hurdles, chimney swifts are long-lived birds, and exhibit a high degree of nest site fidelity. Individuals have been documented returning to the same nest site for up to 11 years.

Having evolved to nest in large, hollow trees, chimney swifts were exposed to a precipitous loss of habitat as Europeans colonized the eastern U.S. and harvested much of the old growth forest. However, with the settlement of the new world came chimneys, which ultimately proved to be an adequate substitute. Older chimneys made of brick or block have a porous, textured surface that is suitable for the swifts to grasp. As more of the virgin forests were lost to man, more chimneys sprang up, leading the way for chimney swifts to alter their nesting and roosting strategies to embrace manmade structures.

The breeding range of the chimney swift now comprises the entire eastern United States and into southeastern Canada. However, the population center for the species is in the heart of the southeast. The following distribution map for chimney swifts reflects the results of Breeding Bird Survey data for the last 34 years.