Spalding's campion (Silene spaldingii) COSEWIC assessment and status report: chapter 11

Technical Summary

Silene spaldingii

Spalding’s campion – silène de Spalding

Range of Occurrence in Canada:
British Columbia

Extent and Area Information

Extent of occurrence (EO) (km²)
[area of single site known] <1 km²
Specify trend in EO :
Unknown
Are there extreme fluctuations in EO?
Unknown
Area of occupancy (AO) (km²)
[approximate area occupied by plants] <1 km2 (300 m²)
Specify trend in AO :
Unknown
Are there extreme fluctuations in AO?
Unknown
Number of known or inferred current locations :
1
Specify trend in # :
Stable
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat :
Decline

Population Information

Generation time (average age of parents in the population) :
Unknown (perhaps several years)
Number of mature individuals :
Unknown but perhaps <100 to perhaps 200?
Total population trend:
Unknown
% decline over the last/next 10 years or 3 generations.
N/A
Are there extreme fluctuations in number of mature individuals?
Unknown
Is the total population severely fragmented?
Yes
Specify trend in number of populations :
Stable
Are there extreme fluctuations in number of populations?
Unknown
List populations with number of mature individuals in each:
<100 to perhaps 200?

Threats (actual or imminent threats to populations or habitats)

  • Current threats most directly affecting the species are likely the invasion of non-native species reducing available habitat and several years of drought forcing extended periods of dormancy that could reduce viability and cause plant deaths.
  • Potential and historic threats pertain primarily to habitat loss, habitat degradation, habitat fragmentation, and agricultural practices such as chemical spraying (herbicides), livestock grazing and trampling, and fire suppression.

Rescue Effect (immigration from an outside source)

Status of outside population(s)?
USA:  Declining
Is immigration known or possible?
Possible
Would immigrants be adapted to survive in Canada?
Yes
Is there sufficient habitat for immigrants in Canada?
Unknown
Is rescue from outside populations likely?
Perhaps possible over a longer period of time but unlikely over the course of several generations and under drought conditions presently experienced in the region.

Quantitative Analysis

[provide details on calculation, source(s) of data, models, etc] : N/A

Current Status

COSEWIC: Endangered (May 2005)

Status and Reasons for Designation

Status:  Endangered

Alpha-numeric code:  B1ab (iii)+ ab (iii); C2a (i, ii); D1

Reasons for Designation: This long-lived perennial herb is a globally imperiled species restricted to two small areas west of the Rockies with only a single population in southern British Columbia. The Canadian population is one of the largest populations known but may contain fewer than 250 mature plants. These are at risk from ongoing habitat loss and degradation especially by introduced weeds.

Applicability of Criteria

Criterion A (Declining Total Population): Insufficient data

Criterion B (Small Distribution, and Decline or Fluctuation): Meets Endangered B1ab (iii)+ 2ab (iii) with extent of occurrence and area of occupancy well below critical levels and continuing decline in quality of habitat due to alien weed invasions. This perennial herb does not undergo extreme fluctuations in number of plants but does exhibit a high degree of dormancy during unsuitable growing seasons giving the impression that plants are completely absent or highly reduced in number during some growing seasons. The probability of a rescue effect from nearby US sub-populations is likely very low.

Criterion C (Small Total Population Size and Decline): Meets Endangered C2a (i, ii) with a continuing decline inferred based on alien weed expansion; the number of mature individuals are well below the critical level of 2500 and likely <250 plants, all at a single location.

Criterion D (Very Small Population or Restricted Distribution): Meets Endangered D1 with likely fewer than 250 plants.

Criterion E (Quantitative Analysis): Insufficient data.

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