Rusty blackbird (Euphagus carolinus) COSEWIC assessment and status report: chapter 11
Technical Summary
Euphagus carolinus
Rusty Blackbird – Quiscale rouilleux
Range of occurrence in Canada: Prince Edward Island, Nova Scotia, New Brunswick, Newfoundland and Labrador, Québec, Ontario, Manitoba, Saskatchewan, Alberta, British Columbia, Yukon, NWT and Nunavut
Extent and Area Information
70% of the total North American breeding range of 7.6 million km²:
Population Information
Number of mature individuals
- minimum based on extrapolation of roost counts from 1970s
- maximum based on Breeding Bird Survey data: 110,400 to 1.4 million
- decline of 18.3% in last 10 years
Threats (actual or imminent threats to populations or habitats)
- Habitat loss caused by wetland conversion to agricultural land on wintering grounds
- Some additional localized habitat loss on breeding grounds because of activities such as wetland conversion, creation of hydroelectric reservoirs
- Bird control programs on wintering grounds
Rescue Effect (immigration from an outside source)
Quantitative Analysis
none
Current Status
COSEWIC: Special Concern (2006)
Status and Reasons for Designation
Status: Special Concern
Alpha-numeric code: Not applicable
Reasons for Designation: More than 70% of the breeding range of this species is in Canada’s boreal forest. The species has experienced a severe decline that appears to be ongoing, albeit at a slower rate. There is no evidence to suggest that this trend will be reversed. Known threats occur primarily on the winter range in the United States, and include habitat conversion and blackbird control programs.
Applicability of Criteria
Criterion A: (Declining Total Population): Does not meet criterion - population decline < 30%.
Criterion B: (Small Distribution and Decline or Fluctuation): Does not meet criterion - Extent of Occurrence > 20,000 km² and Area of Occupancy > 2,000 km².
Criterion C (Small Total Population Size and Decline): Does not meet criterion - total population size > than 10,000.
Criterion D: (Very Small Population or Restricted Distribution): Does not meet criterion - population size > than 1,000 and Area of Occupancy > than 20 km².
Criterion E: (Quantitative Analysis): None
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