COSEWIC Assessment and Status Report on the Common Nighthawk in Canada
- Assessment Summary
- Executive Summary
- COSEWIC History, Mandate, Membership and Definitions
- Lists of Figures and Tables
- Species Information
- Population Sizes and Trends
- Limiting Factors and Threats
- Special Significance of the Species
- Existing Protection or Other Status Designations
- Technical Summary
- Acknowledgements and Authorities Consulted
- Information Sources and Biographical Summary of Report Writer
COSEWIC Status Report
The common English name of Chordeiles minor (Forster, 1771) is Common Nighthawk. The common French name is “Engoulevent d’Amérique”. Its taxonomy is as follows:
Seven subspecies are generally recognized in North America (Poulin et al. 1996), of which three are found in Canada. C. m. minor breeds from southeastern Alaska to Vancouver Island, and from southern Canada including all Canadian provinces, to Virginia, North Carolina, Georgia, and Oklahoma. This subspecies is distinguished from the others by its darker ventral bars (Poulin et al. 1996). C. m. sennetti, occurs primarily in the Great Plains, eastern Montana, southern Saskatchewan and southern Manitoba, to North Dakota, Minnesota and Iowa, and is generally paler than the other subspecies. C. m. hesperis breeds in southwestern Canada, particularly in British Columbia and Alberta, and in the United States, in Washington, Montana, Nevada, Utah, the extreme north of Colorado and western Wyoming. The latter subspecies is similar to C. m. minor but has more grey and white. The differences between these subspecies are slight, and significant introgression zones have been noted (Salt and Wilk, 1958).
This report will cover the species as a whole.
The Common Nighthawk is a medium-sized bird (i.e. 21–25 cm long, 65–98 g; Poulin et al. 1996), and is characterized by long, slender, pointed wings and by a long, slightly notched tail (Poulin et al. 1996). This species has a rather large, flattened head, large eyes, a small bill and a large mouth. The species has cryptic colouration, generally dark brown, with black, white and buff mottling on the wings and upper parts and fine buff bars on the under parts. Females can be distinguished from males by their throat band, which is buff rather than white. In flight, adults have a pronounced white patch at the base of the primaries, which are also dark brown. The tail is brown with fine buff bars and males also have a white band near the tip. Juveniles are distinguished from adults primarily by the absence of the white or buff throat band.
The Common Nighthawk resembles three other species that occur in Canada: Whip-poor-will (Caprimulgus vociferus), Common Poorwill (Phalaenoptilus nuttallii) and Chuck-will’s-widow (C. carolinensis). It can be distinguished from these species by the lack of rictal bristles (long, fine feathers surrounding the bill), the presence of white patches on the primaries, the shape of the tail and its coloration patterns, and by its long pointed wings.
Few molecular or genetic studies have been conducted to distinguish the Common Nighthawk from the other species in the family. The species is considered to be closely related to the Antillean Nighthawk (C. gundlachii) of southern Florida, the Bahamas and Greater Antilles. The two species were considered conspecifics until 1982, when they were separated because of differences in their calls, size, egg colouring and juvenile plumage, as well as their allozymic differences (Poulin et al. 1996).
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