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COSEWIC assessment and status report on the Bog Bird’s-foot Trefoil in Canada

Technical Summary

Lotus pinnatus

bog birds-foot trefoil

lotier à feuilles pennées

Range of Occurrence in Canada: British Columbia

Extent and Area Information

Extent of occurrence (EO) (km2)
(Polygon encompassing all known sites)
100 km2
Specify trend in EOdecline
Are there extreme fluctuations in EO?no
Area of occupancy (AO) (km2)
(Area occupied by plants)
<<1 km2 (<0.06 ha)
Specify trend in AOdecline
Are there extreme fluctuations in AO?no
Number of known or inferred current locations7 populations
Specify trend in #historic decline
Are there extreme fluctuations in number of locations?no
Specify trend in area, extent or quality of habitatdeclining

Population Information

Generation time (average age of parents in the population)several years (3-5 years?)
Number of mature individuals1500-2000
Total population trenddeclining (largest population will be significantly reduced if proposed development proceeds)
% decline over the last/next 10 years or 3 generationspossibly 25% loss inferred if development proceeds
Are there extreme fluctuations in number of mature individuals?no
Is the total population severely fragmented?yes
Specify trend in number of populationsdecline
Are there extreme fluctuations in number of populations?no

List populations with number of mature individuals in each«:

  1. Harewood Plains North: 1500
  2. Harewood Plains South 1: 25
  3. Harewood Plains South 2: 10
  4. Woodley Range: 120-140
  5. Gabriola Island: 65-70
  6. Nanaimo, west of Cinnabar Valley: 40
  7. Nanaimo, south of Extension: 30-45

Threats (actual or imminent threats to populations or habitats)

- loss, degradation and fragmentation of habitat from proposed development and recreational use of all-terrain vehicles; invasive species

Rescue Effect (immigration from an outside source)

Status of outside population(s)?
USA: Stable in some jurisdictions, uncertain in others
Is immigration known or possible?unlikely
Would immigrants be adapted to survive in Canada?unknown
Is there sufficient habitat for immigrants in Canada?uncertain
Is rescue from outside populations likely?unlikely

Quantitative Analysis

Not Applicable

Other Status

Status and Reasons for Designation

Alpha-numeric code:
B1ab(ii,iii,v)+2ab(ii,iii,v); C1
Reasons for Designation:
Few small fragmented populations that are geographically restricted and found within wetland meadows of limited occurrence and considerably disjunct from the main range of the species in the northwestern United States. Populations are at risk from continued habitat loss and encroachment of invasive species and from recreational off-road vehicular activities with the likelihood of significant losses due to planned commercial development of habitat supporting the only sizeable remaining population.

Applicability of Criteria

Criterion A (Declining Total Population):
Not Applicable.
Criterion B (Small Distribution, and Decline or Fluctuation):
Endangered due to small distribution and decline under B1 and B2 (a) +(b, ii, iii, v) with EO about 100 km2 and AO <1 ha and highly fragmented localities with continuing decline anticipated in area of occupancy, area and quality of habitat and number of mature individuals.
Criterion C (Small Total Population Size and Decline):
Endangered under C1 as a consequence of a small total population of 1500-2000 plants with continuing decline projected of about 25% if development of major site proceeds.
Criterion D (Very Small Population or Restricted Distribution):
Threatened under D2 due to the species’ small AO <20 km2 and only 7 localities
Criterion E (Quantitative Analysis):
Not Applicable.