Northern bobwhite (Colinus virginianus) COSEWIC status report: chapter 12

Technical Summary

Colinus virginianus

Northern Bobwhite

Colin de Virginie

Range of Occurrence in Canada: ON

 

Extent and Area Information (from Ontario Breeding Bird Atlas 1981-1985 and 2001-2003)

·        Extent of occurrence (EO)(km²) : ca 28,000 km2

·        Specify trend in EO : probably stable

·        Are there extreme fluctuations in EO? no

·        Area of occupancy (AO) (km²) : less than 1000 km2

·        Specify trend in AO : declining

·        Are there extreme fluctuations in AO? No

·        Number of extant 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 : declining

 

Population Information

·        Generation time (average age of parents in the population) : 2-3 years

·        Number of mature individuals : certainly less than 1000, probably less than 500

·        Total population trend: declining

·        % decline over the last/next 10 years or 3 generations. 88% (Breeding Bird Survey)

·        Are there extreme fluctuations in number of mature individuals? No

·        Is the total population severely fragmented? Yes

·        List populations with number of mature individuals in each (from addendum) :

WalpoleI.:  230

Other small, scattered populations, many (?) the result of repeated introductions

·        Specify trend in number of populations : decrease of 76% since 1985 (Ontario Breeding Bird Atlas)

·        Are there extreme fluctuations in number of populations? No


Threats (actual or imminent threats to populations or habitats)

·        continued loss of agricultural and native prairie habitat

·        degradation of habitat through increase in size of individual cultivated fields, loss of fencerows, loss and increasing isolation of brushy cover

·        food sources depleted through pesticides and herbicides

·        increasing predator (house cat, raccoon, fox, coyote, skunk, opossum) populations

·        dilution of native gene pool through repeated reintroductions from varied stocks

 

Rescue Effect (immigration from an outside source) : LOW

·        Status of outside population(s)?

USA:  Declining

[other jurisdictions or agencies] present in Mexico but status unknown

·        Is immigration known or possible? Unlikely

·        Would immigrants be adapted to survive here? Yes

·        Is there sufficient habitat for immigrants here? Declining

·        Is rescue from outside populations likely? No

·        If the species is extirpated in Canada, is suitable stock available from outside Canada for reintroduction? Yes, though genetic purity is questioned

Quantitative Analysis : n.a.

Current Status

COSEWIC: Endangered

Other sources of information : Addenda by Richard J. Cannings, COSEWIC Bird SSC Co-chair  and Ontario Ministry of Natural Resources

 

Status and Reasons for Designation

Status:   Endangered

Alpha-numeric code:

A2b; C1, C2ai

also meets criteria for Threatened  A2c, B2a, B2bii, iii, iv, v and D1

Reasons for Designation:

This species depends on native prairie and old meadow habitats that have largely disappeared from its southern Ontario range.  Its population has declined drastically over the last 30 years and shows no sign of significant recovery.  There is perhaps only one viable population in Canada, on Walpole Island, Ontario.  The status of this species is complicated by the presence of many introduced populations which typically do not persist and whose genetic composition may pose a threat to native populations.

Applicability of Criteria:

Criterion A (Declining Total Population): A2b: meets Endangered > 50 % decline.

Criterion B (Small Distribution, and Decline or Fluctuation): Meets Threatened B2b (ii, iii, iv,v).

Criterion C (Small Total Population Size and Decline): Probably meets Endangered C1 (population <2,500) but the numbers from Walpole Island are difficult to determine. Almost meets C2a(ii).

Criterion D (Very Small Population or Restricted Distribution): Meets Threatened D1, based on small population.

Criterion E (Quantitative Analysis): not available

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