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Information about the Chimney Swift

Praseeda Shirodkar
Many people recognize chimney swifts from the noises coming from their chimneys during the months they are not in use. We give you some information about the bird, chimney swift.

Did You Know?

A Chimney swift can consume as much as one-third of its body weight (approx. 0.7 oz. or 21 g) in insects daily. A single swift is able to consume 17,500 mosquitoes or 280 termites a day!

Chimney swifts

Chimney swifts are birds that are known for roosting and building their nests in chimneys, hence their name. They belong to the swift family Apodidae. They are the members of genus Chaetura and their scientific name is Chaetura pelagica. These birds were abundant in North America.
However, today, there is a decline in the number migrating here. They are very similar to Vaux's swift and Chapman's swift. Sometimes, they are mistakenly considered to be swallows.


Described as a 'flying cigar', a chimney swift is a small bird that is dark gray to brownish-gray in color with a lighter-shaded throat. They have a slender body and their wings are long, narrow, and curved. Their heads are small and round while their necks are short. They have small beaks. Their tail is short with stiff spiny feather tips.
Their legs and feet are designed in a manner that helps them cling on to vertical surfaces only. This bird is known to have a wingspan of about 12 inches which is one of its distinct attributes.


Originally, hollow trees and cliffs in the forests of North America (Eastern half) were their habitats. They have been substituted by man-built structures such as the chimneys.
However, they also inhabit vertical enclosed areas such as air vents, hollow trees, and caves. They use open areas to look for food. They also search in forests, over ponds, or in residential areas.
Their summers and springs are spent in the U.S. from Texas to Florida and up into Canada. However, their winters are spent in the Amazon in Peru and Brazil.


The sound made by these birds can be described as a loud and fast twitter series that lasts for about 3 seconds. At times, it may give single chirps.

Eating Habits

They are known to forage on the wing and mostly feed on ants, flies, stoneflies, crane flies, fleas, wasps, bees, aphids, and other flying insects. Airborne spiders that drift on threads are also consumed by chimney swifts. They also prey on pest species like the red imported fire ant and the clover root curculio.


During summer (March and April), these birds migrate in flocks to the North and for winter, they return to the South. These birds are known to migrate long distances i.e. they migrate to South America each winter, passing the Gulf of Mexico or move along the border of the Texas coast.
Furthermore, most of these birds use one of the three distinct flyways, which are, the Atlantic coast, the east side of Appalachians, and the Mississippi river.
They head to the South for winter from late September to early October and this is the time they feed and make nests. Between the months of May and July, they reproduce.


These birds fly all day long i.e. they are constantly flying, catching insects as they go; be it for feeding their young ones or themselves. They even bathe and mate during flight. They are not able to perch like other birds and come to rest or settle only at night and to feed their young ones.
It is believed that a chimney swift can fly about 1,000 miles in one day and over one million miles in its lifetime. Considering the distance they cover, they are referred to as migratory birds.
They usually have a rapid motion with prompt turns, steep climbs, and short glides. Their wing-beats are fairly shallow. Their rapid movements are also alternated with graceful long glides wherein they raise their wings in a V-pattern along with a side-to-side rocking motion.

Other Facts

Controlling insect populations

These birds are highly beneficial for the environment as they help in controlling insect populations that include pest species such as flying ants, mosquitoes, biting flies, wasps, termites, etc.
A strange thing about their flight is that the wings of these birds appear to be beating one at a time, whereas studies reveal that the wings beat in synchrony. This illusion may be due to their rapid and erratic flight motion.

Bathe while flying

Chimney swifts bathe while flying. They do this by flying low and touching the surface of a water body with their chest, and then getting rid of the water from their feathers by shaking them.
They may assemble in large flocks and roost together in one place when not breeding. However, they never nest colonially and each pair needs its own nest site.

Building Nest

The nests that they build are saucer-shaped which they make using twigs that they break off from branches. They make use of their feet while flying for breaking the twigs and later, hold them in their beak on reaching the nest site. They then build their nest with these loosely woven twigs and then stick it on the wall with their glue-like saliva.
Their nest measures about 2 to 3 inches (front to back), is 4 inches wide, and 1 inch deep. Their nests do not pose any kind of health hazards in a properly maintained chimney. They lay three to seven eggs which should be incubated for around 21 days. Their young ones remain dependent for food for about thirty days.


There is a considerable decline in the population of these birds since the 1980s, as a result of removal or lesser favored breeding sites. Due to this, these birds are now protected by the U.S. Migratory Bird Act, with special towers being built to provide them with nesting sites in order to increase their population.
Conservation efforts at an individual level can include the following:
  • Plant native trees, shrubs, etc. that attract more insects (mainly flying insects) that are essential for these birds during their breeding season.
  • Do not cap the chimneys, thus allowing the birds to nest.
  • Promote the building of chimney swift towers in parks and other places in your neighborhood.
  • Help in spreading the awareness of the need for chimneys (made of stone or firebricks) without caps.

Other Concerns

Most people tend to get rid of these birds from their chimneys due to their loud annoying sounds. However, these sounds are the feeding calls of baby birds that do not last for long. Moreover, they make the most noise only during the last two weeks before they leave. Blankets or towels can be stuffed in the fireplace in order to lessen the noise.
Chimneys that make use of smaller metal flue pipes instead of clay liners, may be a threat to these birds, as it would be difficult for them to grip the slippery metal surface. Thus, they should always be capped.
The nests of these birds are safe and are not a fire hazard as they are very small. However, it is necessary to remove the nests once the young ones have left. This is because if used by a swift that has returned, there is a possibility of the nest collapsing during the nesting period. Moreover, the bird parasites would also get cleared.
The annual cleaning of the chimney can be done once the baby birds have left the nest. Chimney swifts are protected under the Migratory Bird Treaty Act, and any individual who has knowingly destroyed birds or their nests with eggs or the young ones, can be fined or penalized.
In spite of the annoying sounds that one may have to hear, it is necessary to know that chimney swifts can be highly beneficial as they are efficient natural pest control agents. Moreover, these birds are visitors during the summer season, when the fireplace is dormant.