Horned lark, strigata subspecies COSEWIC assessment and status report: chapter 12

Technical Summary

Eremophila alpestris strigata

Horned Lark, strigata ssp. - Alouette hausse-col, de la sous-espèce strigata

Range of Occurrence in Canada:
British Columbia

Extent and Area Information

Extent of occurrence (EO)(km²)
<10 km²
Specify trend in EO:
Decline
Are there extreme fluctuations in EO?
No
Area of occupancy (AO) (km²)
Only one sighting of a territorial male <1 km²
Specify trend in AO:
Decline
Are there extreme fluctuations in AO?
No
Number of extant locations:
10
Specify trend in #:
Decline
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat:
Declining (extent and quality)

Population Information

Generation time (average age of parents in the population):
1 year
Number of mature individuals:
0 – 5
Total population trend:
Decline
% decline over the last/next 10 years or 3 generations.
> 90% decline since 1970s (possibly extirpated)
Are there extreme fluctuations in number of mature individuals?
N/A
Is the total population severely fragmented?
Yes
Specify trend in number of populations:
Decline
Are there extreme fluctuations in number of populations?
No
List populations with number of mature individuals in each:
Vancouver Island (0-1)

Threats (actual or imminent threats to populations or habitats)

  • Habitat loss on Vancouver Island due to urbanization
  • Intensification of agriculture practices in the Fraser Valley
  • Destruction of shoreline habitat due to dikes (Vancouver Delta)
  • Invasive species (Vancouver Island)
  • Increase in predators (everywhere)
Rescue Effect (immigration from an outside source)
Low
Status of outside population(s)?
Yes
USA: candidate for Endangered
Is immigration known or possible?
Possible
Would immigrants be adapted to survive here?
Yes
Is there sufficient habitat for immigrants here?
Yes
Is rescue from outside populations likely?
No

Quantitative Analysis

N/A

Current Status:

not previously assessed by COSEWIC

Status and Reasons for Designation

Status: Endangered

Alpha-numeric code: B1ab(i-v)+2ab(i-v); C2a(i); D1

Reasons for Designation: Although this species has always been rare in Canada, it has declined steadily throughout its range over the last 50 years and it is currently nearly extirpated in Canada.

Applicability of Criteria

Criterion A (Declining Total Population): Not applicable; no numerical data for decline

Criterion B (Small Distribution, and Decline or Fluctuation): Meets Endangered B1ab (i-v) because of very small distribution and declines in all criteria, and Endangered B2ab(i-v) because of small area of occupancy and decline.

Criterion C (Small Total Population Size and Decline): Meets Endangered C2a(i) because of observed decline and fragmented population--Canadian population is somewhat disjunct from US and is very small (certainly less than 250).  C1 not applicable because there are no numerical data for decline.

Criterion D (Very Small Population or Restricted Distribution): Meets Endangered D1 because of very small population (certainly less than 250)

Criterion E (Quantitative Analysis): Not done.

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