Chimney swift (Chaetura pelagica) COSEWIC assessment and status report: chapter 2
Sometimes mistaken for a swallow, the Chimney Swift is readily distinguished by its cigar-shaped body, long, narrow, pointed wings, short spiny tail and quick, jerky flight. The folded wings project beyond the tail. The plumage is dark brownish except for the paler throat. All ages and sexes are similar in appearance.
The breeding range of the Chimney Swift is limited to eastern North America. In Canada, it breeds in east central Saskatchewan, southern Manitoba, Ontario, Quebec, New Brunswick, Nova Scotia and possibly Prince Edward Island and Newfoundland. Approximately one quarter of the species’ breeding range is located in Canada. In the United States, the Chimney Swift is found westward to Montana, eastward to New England and southward to Texas and Florida. It winters in the upper Amazon River drainage basin in South America, mainly in Peru, as well as southern and northeastern Ecuador, northwestern Brazil and northern Chile.
Chimney Swifts are aerial foragers, often concentrating near water where insects are abundant. Before the arrival of Europeans in North America, the Chimney Swift mainly used hollow trees for nesting sites; when hollow trees became rare as a result of logging, it quickly adopted chimneys. The Chimney Swift is now mainly associated with urban and rural areas where chimneys are available for nesting and roosting. In their northern breeding range, Chimney Swifts look for sites with a relatively constant ambient temperature. Winter habitat extends from river-edge forest and edge of tropical lowland evergreen forest to farmland and suburban and central city zones.
The Chimney Swift is monogamous and generally first breeds at two years of age. Pairs stay together for many years, returning every year to the same nesting site. Each pair occupies and defends its own nest site. The nest is a half-saucer made of small twigs attached together and to a vertical surface with the swifts’ glutinous saliva. Mean clutch size is four eggs. Only one clutch is produced annually in Canada. Fledging success varies between 70 and 86% with a mean of 3 young fledged per nest. In the fall, large flocks of Chimney Swifts travel to the southern United States (Texas, Louisiana), where they cross the Gulf of Mexico and then fly down the Atlantic coast until they reach South America. They follow much the same route in reverse in the spring.
Population Sizes and Trends
The Chimney Swift population in Canada is estimated at 11 820 individuals (Quebec 2 520; Ontario 7 500; Maritimes 900; all other provinces 900). Chimney Swift populations are declining throughout its range. In the last 15 to 20 years, the area of occupancy in Ontario and Quebec decreased by 46% and 35% respectively. According to Breeding Bird Survey (BBS) data, the Canadian population has declined 7.8% per year from 1968 to 2005, for an overall 95% reduction. There have been significant declines in all Canadian provinces where data are available. This decline has slowed to 2.37% per year over the last 15 years indicating a loss of about 28% during the last 3 generations (13.5 years). In North America, the species has declined 1.6% annually since 1966. In the United States, 58% of the states where data are available report a significant decline for the 1966-2005 period.
Limiting Factors and Threats
The most significant limiting factor to Chimney Swift populations is the dwindling number of breeding and roosting sites resulting from logging, the disappearance of old, abandoned buildings, and most importantly the dramatic reduction in the number of suitable and accessible traditional chimneys, the species’ main breeding habitat. The growing use of electric and gas heating, the renovation needs of old traditional chimneys, new fire prevention standards (adding a metal pipe inside brick chimneys, installation of spark arresters, chimney hats and protective fencing against nuisance animals) have reduced the number of traditional chimneys available for swifts. The rate at which chimneys are being converted is rising and hardly any suitable sites will remain in 30 years or so. In Quebec, the number of nesting sites is now limited and it is estimated that only 60% of breeding adults actually reproduce; the situation is likely similar elsewhere in Canada.
Bad weather during the breeding season can cause mass mortality events. The frequency of such weather extremes may also increase as global warming continues. Other threats facing the species are chimney sweeping during the breeding period, pesticide spraying, and the intolerance of some building owners.
Special Significance of the Species
The Chimney Swift is the only swift found in eastern North America. The species has aroused a great deal of interest among the public and birdwatchers. Since Chimney Swifts are mostly found in cities and towns, they are relatively easy to spot and their spectacular entrances into their roosts never fail to fascinate people. A number of these sites are renowned and numerous visitors admire the spectacle of hundreds of birds entering their roosting chimneys at sunset. Individual Chimney Swifts are capable of eating more than 1000 insects per day.
At present, the Chimney Swift does not have any special protection in Canada and the United States outside that provided by the Migratory Birds Convention Act. The species does not appear on any Canadian, US or World Conservation Union (IUCN) lists of threatened species. There is no known form of protection for the species in its winter range or during migration outside Canada and the United States.
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