The chimney swift may be an example of a species that benefits from human development. Prior to human habitation of the U.S. the species made its home in caves and tree hollows, but with the invention of the chimney the birds found a new nest site. As humans spread, so did the birds, until the recent innovation of covered narrow flue chimneys. The birds are now back in decline as man-made nesting sites become less readily available.
The chimney swift grows to around 6 inches in length with a wingspan just under 12 inches, and weighs up to 1 ounce, on average. It has an almost black plumage with a few areas of white that sometimes give a more dark gray appearance. The bird has the characteristic swift body shape of long, swept back, pointed wings but has a more rounded and stiff bristled tail. When the wings are against the body during flight the bird has a very cigar shaped appearance.
Habitat and Range:
The chimney swift is a migratory bird with no solid home range. It spends the breeding season in the eastern half of the U.S. and as far north in Canada as Alberta and New Foundland. When winter comes, the birds travel south through Central America into northern South America. The bird tends to spend most of its time flying, feeding and bathing while in the air. Swooping low over a body of water, the swift dips its chest into the water to help clean itself. When roosting, the swift tends to be found on the edges of woodland areas near a freshwater source.
Diet and Predators:
The bird is what is known as an insectivore, meaning it only eats small insects which it can catch on the wing. It will take flying insects in the air and swoop down to pluck spiders and terrestrial insects from tree limbs and leaves. Because they fly so constantly they do not have to worry much about predators from the ground. Hawks and falcons are able to match speed and agility with the small birds and will often prey on them given the chance.
Chimney swifts pair off for life, remaining with the same partner for eight or nine years barring the death of one partner. The birds breed between May and July each year, generally producing one brood, but in good years may manage two. Nests are commonly built in dark hollows such as chimney stacks or tree holes out of small twigs and sticks held together with a sticky mucus. A typical clutch is around five eggs which take up to 21 days to hatch. The task of incubating and feeding the chicks is shared by both adults until the young leave the nest after 14 to 19 days. In the wild, the swifts can live for up to an average of 10 years.