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COSEWIC Assessment and Status Report on the Red Knot in Canada

Technical Summary

Calidris canutus rufa

Red Knot, rufa subspecies
Bécasseau maubèche, de la sous-espèces rufa

Range of Occurrence in Canada:  NU, NT, BC, AB, SK, MB, ON, QC, NB, NS, PE, NL


Extent and Area Information

Extent of occurrence (EO)(km2)
Area of breeding range derived from information compiled from distribution maps
205 534 km2 (breeding)




Specify trend in EO

Unknown

Are there extreme fluctuations in EO?

No

Area of occupancy (AO) (km2)
Based on area of suitable habitat on classified land cover maps

128 375 km2 (breeding)



Specify trend in AO

Probably stable on breeding grounds

Are there extreme fluctuations in AO?

No

Number of known or inferred current locations

N/A


Specify trend in #

N/A

Are there extreme fluctuations in number of locations?

N/A


Specify trend in area, extent or quality of habitat

Probably stable on breeding grounds. Decrease in migration habitat


Population Information

Generation time (average age of parents in the population)
4-5 years


Number of mature individuals

13 500 – 15 000

Total population trend:

Decline

% decline over the last/next 10
years or 3 generations.
15 year (three generations) trend calculated over entire wintering area
in Tierra del Fuego and Patagonia

70.5%





Are there extreme fluctuations in number of mature individuals?

No


Is the total population severely fragmented?

No


Specify trend in number of
populations

N/A


Are there extreme fluctuations in number of populations?

N/A

List populations with number of mature individuals in each:


Threats (actual or imminent threats to populations or habitats)

- reduction in major food supply (eggs of horseshoe crab) in Delaware Bay on northward migration,
- habitat loss (coastal wetlands) along migration routes. 
- other threats include changing weather patterns (increased hurricanes and tropical storms), pollution, disturbance

Rescue Effect (immigration from an outside source): No

Status of outside population(s)?
USA: (Not applicable).

Is immigration known or possible?
No interchange has been detected between main biogeographic groups wintering in the Americas.

Not known




Would immigrants be adapted to survive in Canada?

Not applicable


Is there sufficient habitat for immigrants in Canada?

Not applicable


Is rescue from outside populations likely?
Repopulation from other biogeographic groups of knots would not be anticipated.

No





Quantitative Analysis


Current Status

COSEWIC: Endangered (2007)


Status and Reason for Designation

Status: Endangered
Alpha-numeric code: A2b

Reasons for Designation: This subspecies is a medium-sized shorebird that breeds only in Arctic Canada and migrates thousands of kilometres between its Arctic breeding grounds and wintering areas at the tip of South America. The subspecies has shown a 70% decline in abundance over the past three generations (15 years). It is threatened by a depletion of horseshoe crab eggs, a critical food source used during northern migration. There is no potential for rescue from other populations.


Applicability of Criteria

Criterion A: (Declining Total Population): Meets Endangered A2b because population has declined by 70% in 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): Not applicable.

 

Calidris canutus roselaari type

Red Knot, roselaari type
Bécasseau maubèche, de type roselaari

Range of Occurrence in Canada:  BC, YT, NT


Extent and Area Information

Extent of occurrence (EO)(km2)
Breeding area derived from information compiled from distribution maps

Florida/SE US and Maranhão: unknown
Pacific coast: 417 396 km2

Specify trend in EO

Unknown

Are there extreme fluctuations in EO?

No

Area of occupancy (AO) (km2)
Based on area of suitable habitat in breeding area on classified land cover maps

Florida/SE US and Maranhão: unknown
Pacific coast: 25 856 km2



Specify trend in AO

Stable on breeding grounds

Are there extreme fluctuations in AO?

No

Number of known or inferred current locations

N/A


Specify trend in #

N/A

Are there extreme fluctuations in number of locations?

No


Specify trend in area, extent or quality of habitat

Probably stable on breeding grounds. Decrease on migration routes and some wintering sites


Population Information

Generation time (average age of parents in the population)
4-5 years


Number of mature individuals
Florida/SE US: 3 375, Maranhão: 5 700, Pacific coast: 1 500-3 000

Combined population: 12 825



Total population trend:

Florida/SE US: Decline
Maranhão: stable (?) -- decline.
Pacific coast: decline

% decline over the last/next 10
years or 3 generations.
15 year (three generations) trend calculated on the wintering areas. Florida/SE US: 70%, Maranhão: 7% (?), Pacific coast: 60% (see text for calculation)

Combined trend: 47%







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: see above


Threats (actual or imminent threats to populations or habitats)

Florida/SE US and Maranhão:
- reduction in major food supply (eggs of horseshoe crab) in Delaware Bay on northward migration
- habitat reductions (coastal wetlands) along migration routes
- degradation of wintering sites in Florida through development Pacific coast:
- developments in California (e.g., San Francisco Bay) affecting wintering and migrating birds
- habitat degradation along migration routes
- other threats include changing weather patterns (increased hurricanes and tropical storms), pollution, disturbance

Rescue Effect (immigration from an outside source): No

Status of outside population(s)?
USA: (Not applicable).

Is immigration known or possible?
No interchange has been detected between main biogeographic groups wintering in the Americas.

Not known




Would immigrants be adapted to survive in Canada?

Not applicable


Is there sufficient habitat for immigrants in Canada?

Not applicable


Is rescue from outside populations likely?
Repopulation from other biogeographic groups of knots would not be anticipated.

No





Quantitative Analysis

No analyses available


Current Status

COSEWIC: Threatened (2007)


Status and Reason for Designation

Status: Threatened
Alpha-numeric code: A2a

Reasons for Designation: This designatable unit includes the subspecies roselaari and two other populations that winter in Florida and northern Brazil and that seem to share characteristics of roselaari. The subspecies roselaari migrates through BC and breeds in Alaska. The migration routes and breeding areas of the other two populations are unknown. This group has declined by 47% overall during the last three generations (15 years). Ongoing threats include habitat loss and degradation on wintering sites and, for the Florida/SE US and Maranhão groups, depleted levels of horseshoe crab eggs, a critical food source needed during northward migration. Rescue from other populations is not anticipated.


Applicability of Criteria

Criterion A: (Declining Total Population): Meets Endangered A2a because population has declined by 47% over 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):

 

Calidris canutus islandica

Red Knot, islandica subspecies
Bécasseau maubèche, de la sous-espèces islandica

Range of Occurrence in Canada:  NU, NT


Extent and Area Information

Extent of occurrence (EO) (km2)
Area of breeding range in Canada derived from information compiled from distribution maps
455 669 km2




Specify trend in EO

Unknown

Are there extreme fluctuations in EO?

No

Area of occupancy (AO) (km2)
Based on area of suitable habitat in breeding grounds in Canada on classified land cover maps

284 611 km2




Specify trend in AO

Probably stable on Canadian breeding grounds

Are there extreme fluctuations in AO?

No

Number of known or inferred current locations

N/A


Specify trend in #

N/A

Are there extreme fluctuations in number of locations?

N/A


Specify trend in area, extent or quality of habitat

Probably stable on breeding grounds. Decrease in wintering areas


Population Information

Generation time (average age of parents in the population)
4-5 years


Number of mature individuals
81 000: based on 40% of total breeding population (202 500) in Canada

81 000



Total population trend:

decline

% decline over the last/next 10
years or 3 generations.
Trend between 1998 and 2003, although likely similar over the last 15 years (3 generations)

17%





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: see above


Threats (actual or imminent threats to populations or habitats)

- overharvesting of shellfish on Dutch Wadden Sea
- habitat degradation in wintering areas

Rescue Effect (immigration from an outside source): Possible

Status of outside population(s)?
Declining in Europe
[other jurisdictions or agencies] (Not applicable).

Is immigration known or possible?

Possible


Would immigrants be adapted to survive in Canada?

Yes


Is there sufficient habitat for immigrants in Canada?

Yes


Is rescue from outside populations likely?

Possible rescue from breeding populations in Greenland


Quantitative Analysis


Current Status

COSEWIC: Special Concern (2007)


Status and Reason for Designation

Status: Special Concern
Alpha-numeric code: not applicable

Reasons for Designation: This subspecies is a medium-sized Arctic breeding shorebird that migrates to wintering grounds in Europe. Forty percent of the breeding population of this subspecies occurs in Canada. This subspecies has declined by 17% over the last three generations (15 years). There are no identified threats to individuals in Canada. Habitat on the Canadian breeding grounds is likely stable, but shellfish harvesting on the wintering grounds in Europe presents an ongoing threat.


Applicability of Criteria

Criterion A: (Declining Total Population): Does not meet criterion.

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): Not applicable.