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COSEWIC Assessment and Status Report on the Common Nighthawk in Canada

Technical Summary

Chordeiles minor

Common Nighthawk
Engoulevent d’Amérique

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

Extent of occurrence (EO)(km2)
Canadian range according to NatureServe calculated by Bird Studies Canada, unpubl. data.
4 817 780 km2




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

Generation time (average age of parents in the population)
2 -3 years


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)

Is immigration known or possible?
Yes

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

Status:  Threatened
Alpha-numeric code: A2b

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.