The swift is readily identified by its fairly uniform sooty grey-brown colour, its resemblance to a 'cigar with wings', and its jerky or flickering flight that gives one the false impression that its long pointed wings are beating alternately. The average chimney swift measures about 13 cm in length from tip to beak to tip of tail, and has a wingspan of about 31 cm. Its chittering vocalizations, likened by some to the clicking of knitting needles, carry for a long distance and can often be heard even when the birds are flying at great heights and are scarcely visible to the naked eye. While the chimney swift may seem to be somewhat reminiscent of a swallow, it is surprisingly much more closely related to the hummingbird.
Chimney swifts winter in western Peru, northern Chile and the upper part of the Amazon River basin of South America. The wintering grounds of the chimney swift were only recently discovered, when coloured metal leg bands from banded birds were found adorning the jewellery of a tribe of aboriginal people in remote sections of Peru. They head north to nest and spend their summers in eastern North America and usually return to New Brunswick in early May. Most swifts leave the province by mid-September.
Once inside the chimney, the birds cling with strong sharp claws to the brick walls, their bodies overlapping like shingles on a roof. Short stiff spine-tipped tail feathers help to prop the birds up in a vertical position. The flocking, aerial display and roosting behaviour patterns may be altered in cold wet weather.
Although most of the migrating swifts disperse to nest, some birds may build their nests in the same chimneys that serve as communal roosts during spring migration. Chimney swifts, will sometimes nest together in large numbers, but small chimneys are usually suitable for only a single nesting pair. Apart from chimneys, other acceptable nesting sites include hollow trees, barns, old buildings, silos, open wells, cisterns, air shafts,crevices in rock cliffs and other dark sheltered place. In the Maritime Provinces, most swifts originally nested, and some still nest, in hollow trees.
The nest is a shallow bracket-like cup constructed of twigs that have been cemented together with glutinous saliva. The clutch of four or five eggs is usually laid in late June or early July and both parents share in incubation duties for 19 to 21 days. The young birds usually are able to fly when 30 days old, and regularly return to the nest after their first flight.
Chimney swifts have been clocked at level flight speeds of up to 234 km/h, and are no doubt faster during aerial dives. They are virtually never seen resting on branches or wires. Although the bill is very small, the mouth is large to facilitate the catching beetles, flies, ants, termites, other flying insects and spiders. The legs of swifts are so small and weak that the birds may have difficulty taking off if they alight on the ground.
The advent of settlement in North America and the construction and maintenance of chimneys may have contributed to a temporary increase in populations of chimney swifts throughout their range, but numbers of these birds have recently decreased in some part of the Maritimes, especially in the vicinity of the New Brunswick-Nova Scotia border.
The marked decline in chimney swift populations in the last 30 years may be related to forest spraying with insecticides, a shortage of old large hollow trees due to intensive forest management, the destruction of old buildings and their chimneys, and a switch to electric heating. During the migration and nesting season, the mortality of swifts may result from a shortage of food during prolonged periods of inclement weather, the building of fires in fireplaces, and the venting of fumes, noxious gases and smoke from chimneys.
A quaint tradition in some Fredericton families was telling children that it was time for them to go to bed when the chimney swifts came in to roost for the night. Unfortunately, many of the chimneys that formally housed chimney swifts have been torn down or sealed up. However, there a few exceptions, including the Incutech Building Chimney on the University of New Brunswick campus
The chimney at the Incutech Building has served as a roosting site for swifts for many years. In fact, a clause in the lease agreement states that "the Lessee shall not disturb or harm the resident population of Chimney Swifts in their quiet use and enjoyment of he chimney shaft of the building". The University of New Brunswick is to be commended for helping to ensure the preservation and protection of this chimney swift haven. It is hoped that this interpretive site will not only provide the public and the opportunity to observe this fascinating creature, but will also help to stimulate an interest in New Brunswick natural history and the environment, and to encourage people to take action to help protect suitable habitat for the wildlife species that share our province.