Common nighthawk (Chordeiles minor) COSEWIC assessment and status report: chapter 13
Technical Summary
Chordeiles minor
Range of occurrence in Canada: Yukon, Northwest Territories, British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick, Prince Edward Island, Nova Scotia, Newfoundland and Labrador
Extent and Area Information
Canadian range according to NatureServe calculated by Bird Studies Canada, unpubl. data.
Specify trend in EO
Stable
Are there extreme fluctuations in EO ?
No
Area of occupancy (AO) ( km2 )
Number of breeding pairs in Canada (200 000)* average territory area of 0.27 km2
Approx. 54 000 km2
Specify trend in AO
Decline
Are there extreme fluctuations in AO ?
No
Number of known or inferred current locations
not applicable
Specify trend in #
not applicable
Are there extreme fluctuations in number of locations?
not applicable
Specify trend in area, extent or quality of habitat
Decline
Population Information
Number of mature individuals
Based on BBS abundance estimates
Approx. 400 000
Total population trend:
% decline over the last/next 10 years or 3 generations.
Based on BBS data: decline of 49.5% in most recent 10 year period (1995-2005)
49.5%
Are there extreme fluctuations in number of mature individuals?
No
Is the total population severely fragmented?
No
Specify trend in number of populations
not applicable
Are there extreme fluctuations in number of populations?
not applicable
List populations with number of mature individuals in each:
not applicable
Threats (actual or imminent threats to populations or habitats)
- Reduced insect abundance due to pesticides
- Habitat loss and alteration in forest, agricultural and urban areas
- Other possible factors include increases in predators in urban and farming areas, collisions with motor vehicles, and climate change
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: significant decline of 1.83% per year (1968-2005)
Would immigrants be adapted to survive in Canada?
Yes
Is there sufficient habitat for immigrants in Canada?
Yes
Is rescue from outside populations likely?
Unlikely because declining throughout its range
Quantitative Analysis
None
Current Status
COSEWIC: Threatened (April 2007)
Status and Reasons for Designation
Reason for Designation: In Canada, this species has shown both long and short-term declines in population. A 49% decline was determined for areas over the last three generations. Reduction of food sources has apparently contributed to the decline of this species, as with several other aerial insectivores. Reductions in habitat availability, caused by suppression, intensive agriculture, and declines in the number ofgravel rooftops in urban areas, may also be factors in some regions.
Applicability of Criteria
Criterion A: (Declining Total Population):
Meets Threatened A2b because population has declined by 49% in the last three generations.
Criterion B: (Small Distribution and Decline or Fluctuation):
Does not meet criterion.
Criterion C: (Small Total Population Size and Decline):
Does not meet criterion.
Criterion D: (Very Small Population or Restricted Distribution):
Does not meet criterion.
Criterion E: (Quantitative Analysis):
None available.
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