About Chimney Swifts

Chimney Swift © Dominic Sherony
Chimney Swift © Dominic Sherony

The Chimney Swift (Chaetura pelagica) is one of the most aerial of birds. They eat entirely in flight, dining on numerous species of flies, beetles, termites, flying ants, bees, wasps, and moths. In addition, these birds drink, collect nesting material, and possibly even copulate "on the wing."

What makes them even more unique is that they are the only breeding bird in Massachusetts that builds its nest and successfully raises its young in chimneys.


Said to look like "a flying cigar," the sooty gray Chimney Swift has a short body (4.5–5.5 inches) and wings that are narrow, slightly curved, and have a spread of 12–13 inches. 

In flight they appear almost bat-like. They fly with rapid, erratic wingbeats that are interspersed with short, quick glides. As they fly through the air, swifts make a loud chattering or twittering call.

Life Cycle

Chimney Swifts are a breeding bird species in Massachusetts. Their spring arrival in New England from their wintering South American grounds coincides with the emergence of flying insects. In late April or early May, both male and female swifts start to build their nests in dark, sheltered locations like chimneys, old wells, air shafts, and sometimes barns or attics.

Chimney Swift nest & eggs © Shawn P. Carey, Migration Productions
Chimney Swift nest © Shawn P. Carey

The half-saucer shaped nest is made of twigs and attached to the inside wall of the chimney with the bird's glutinous saliva. The nest can be placed anywhere from 2 to 22 feet down from the top of the chimney. Four or five eggs are laid every other day during June or July until the clutch is completed. Incubation is by both parents and lasts 18 to 21 days.

After being cared for in the nest for just over two weeks, the young become adventurous and begin to cling to the wall near the nest and take short flights. Some 14 to 18 days later the fledglings leave the nest, returning to the chimney only to rest or roost at night. During this time they feed on their own.

Situations & Solutions

While Chimney Swifts may roost in large numbers in big chimneys or airshafts, only single pairs nest in house chimneys. If a homeowner determines that there is a nest in the chimney—usually by the loud chattering of the young as the parents enter with food—there is no reason for concern. The presence of a nest will not cause a fire or spread disease.

The only time it is necessary to intervene is if an active nest has fallen onto the damper or into the fireplace. In this case, every attempt should be made to return the young to the chimney so the parents can continue to care for them.

Find out what to do >