Skip booklet index and go to page content

COSEWIC Assessment and Update Status on the Northern Goshawk (2000)

Technical Summary

Accipeter gentilis laingi
Northern Goshawk Laingi subspecies
Range of Occurrence in Canada: British Columbia

Extent and Area information

  • extent of occurrence (EO)(km2):
    Vancouver Is:
    31,284 km2
    Queen Char. Is.:
    9,596 km2
    Mainland coast / other islands:
    uncertain
    Total at minimum:
    40,880 km2
    source: status report, pg 15, 4th paragraph

    • specify trend (decline,
      stable, increasinq, unknown)
      unknown


    • are there extreme fluctuations
      in EO (> 1 order of magnitude)?
      no



  • area of occupancy (AO) (km2)
    not specified


    • specify trend (decline,
      stable, increasinq, unknown)
      Possible decline due to logging practises and shortened logging rotations
      source: pg 7 paragraph 3 Pg 16-17


    • are there extreme fluctuations
      in AO
      (>1 order magnitude)?
      no



    • number of extant locations
      n.a.


    • specify trend in # locations (decline, stable, increasing, unknown)
      n.a.



    • are there extreme fluctuations in # locations (>1 order of magnitude)?
      n.a.



    • habitat trend: specify declining, stable, increasing or unknown trend in area, extent or quality of habitat
      Decline due to logging of old-growth forests, and shortened logging rotation. No quantitative information available

Population information

  • generation time (average age of parents in the population) (indicate years, months, days, etc.)
    several years




  • number of mature individuals (capable of reproduction) in the Canadian population (or, specify a range of plausible values)

    • Based on modified habitat capacity model: source - status report, page 14, 2nd paragraph
      425 pairs = 850 individuals



    • Based on survey data, and various extrapolations
      Vancouver Is:
      300 pairs
      Queen Char. Is.:
      50 pairs
      mainland coast and other islands (taxonomy of these birds uncertain):
      75 pairs

      Total:
      425 pairs = 850 individuals
      Excluding mainland:
      350 pairs = 700 individuals
      source- status report, page 15, paragraph 4&5

  • total population trend: specify
    declining, stable, increasing
    or unknown trend in number
    of mature individuals
    unknown





    • if decline, % decline over the last/next 10 years or 3 generations, whichever is greater (or specify if for shorter time period)

    • are there extreme fluctuations in number of mature individuals (>1 order of magnitude)?

  • is the total population severely fragmented (most individuals found within small and relatively isolated (geographically or otherwise) populations between which there is little exchange, i.e.,.s 1 successful migrant / year)?
    No








    • list each population and the number of mature individuals in each
      Apparently only one population is involved. (Little
      is known about population structure. Movements and dispersal are described on pg 12, paragraphs 1&2, and on pg 4, paragraph 3.)


    • specify trend in number of populations (decline, stable, increasing, unknown)
      n.a.




    • are there extreme fluctuations in number of populations (>1 order of magnitude)?
      n.a.




  • Threats (actual or imminent threats to populations or habitats) [add rows as needed]

    Loss and degradation of habitat due to logging of preferred low-elevation, old-growth forest and mature second growth forest. Source: status report pg 7, paragraph 3; pg 16&17.

  • Rescue Effect (immigration from an outside source)
    Low because of low numbers in Alaska



  • does species exist elsewhere
    (in Canada or outside)?
    Alaska



    • status of the outside (population(s)?
      "Species of special concern" for Alaska Dept of Fish & 100-200 pairs - status report, pf!. 14, 2nd paraf!.r.


    • is immigration known or possible?
      yes



    • would immignants be adalJted to survive here?
      yes



    • is there sufficient habitat for immigrants here?
      Contingent on habitat conservation



  • Quantitative Analysis
    Not available