McCown's longspur (Calcarius mccownii) COSEWIC assessment and status report: chapter 11

Technical Summary

Calcarius mccownii

McCown's Longspur – Bruant de McCown

Range of Occurrence in Canada:

Saskatchewan, Alberta

Extent and Area Information

Extent of occurrence (EO) (km²) based on digitized range maps :

212,000 km²

Specify trend in EO :

historic decrease, probably now stable 

Are there extreme fluctuations in EO?

no

Area of occupancy (AO) (km²)

based on estimates of remaining native grassland : 67,000 km² (maximum)

Specify trend in AO :

likely declining with declines in native grassland

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.

Habitat trend :

native grassland habitat lost at annual rate of approximately 1%.

Population Information

Generation time (average age of parents in the population) :

likely 2-3 years 

Number of mature individuals in Canadian population :

375,000 (range: 100,000 - 1,000,000) 

Total Canadian population trend: 

decline over long term

% decline over the last/next 10 years or 3 generations.

  • decline of 98% between 1968 and 2002 based on BBS data
  • decline of 1.5 to 3% between 1996 and 2004 based on BBS and GBM data, respectively stable in last decade

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 :

n.a.

Threats (actual or imminent threats to populations or habitats)

  •  Loss and degradation of grassland habitat
  •  Increased risk of exposure to agricultural pesticides due to use of cultivated fields and seed diet
  •  Use of cultivated fields

Rescue Effect (immigration from an outside source)

Status of outside population(s)?

USA: increase of +1.2%/year between 1966 and 2003 

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?

yes

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: This species has experienced a severe population decline since the late 1960s. This trend appears, however, to have slowed in the past decade. The species is threatened by continuing habitat loss and degradation. It may also risk exposure to pesticides associated with increased breeding in cultivated fields.

Applicability of Criteria

Criterion A: (Declining Total Population): Does not meet criterion - population has been stable over the last 10 years.

Criterion B: (Small Distribution, and Decline or Fluctuation): Does not meet criterion - EO > 20,000 km² and AO > 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 AO > than 20 km².

Criterion E: (Quantitative Analysis): None.

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