Cœur d’Alene salamander COSEWIC assessment and status report: chapter 11
Technical Summary
Plethodon idahoensis
Cœur d’Alene Salamander – Salamandre de Cœur d’Alène
Range of Occurrence in Canada:
British Columbia
Extent and Area Information
Extent of occurrence (EO) (km²)
- Calculated based on minimum convex polygon encompassing all recorded sites: 17,000 km²
- Calculated excluding large extents of unsuitable habitat: 2,000 km²
Specify trend in EO :
Stable
Are there extreme fluctuations in EO?
No
Area of occupancy (AO) (km²)
- Calculated based on a 2 km x 2 km grid, without buffers: 100 km²
- Calculated based on known occurrence sites, with a 1 km buffer: 336 km²
Specify trend in AO :
Stable
Are there extreme fluctuations in AO?
No
Number of known or inferred current locations
The extent of range has become better known in recent years : 56
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)
First reproduction at 3.5 to 4.5 years of age. 5 years
Number of mature individuals
Calculated based on the total of 919 individuals found, about 37% of which are juveniles, and estimating a detectability of 21% (Burton and Likens, 1975) : approximately 2,776 adults among surveyed areas. Probably > 10,000 in total.
Total population trend:
Unknown
% decline over the last/next 10 years or 3 generations.
Unknown
Are there extreme fluctuations in number of mature individuals?
No
Is the total population severely fragmented?
No
Specify trend in number of populations:
Stable
Are there extreme fluctuations in number of populations?
No
List populations with number of mature individuals in each:
no data
Threats (actual or imminent threats to populations or habitats)
Threats include water diversion, sedimentation of interstitial spaces, removal of overstory vegetation, small hydro-electric projects and alterations to hydrology arising from logging. An imminent threat to >20 occurrence sites is highway widening and maintenance with its effects on the traversed streams. Silvicultural activities, such as burning and herbicide application, that are carried out right to the edge of the non-fish bearing streams that support P. idahoensis threaten to damage habitats. Small scale hydro developments divert and channelize streams, destroying habitat. Further threats may include increased isolation of habitat patches and road and trail construction. Climate change, forcing the salamanders to move to higher elevations, may also be a long-term potential threat to this species because of its limited abilities to disperse.
Rescue Effect (immigration from an outside source)
Status of outside population(s)?
USA: S2 in both Montana and Idaho.
Is immigration known or possible?
Although the nearest US site is close to the Canadian border, Plethodon salamanders are very poor dispersers. Immigration is unknown and unlikely to be significant
Would immigrants be adapted to survive in Canada?
Yes
Is there sufficient habitat for immigrants in Canada?
Yes
Is rescue from outside populations likely?
Very unlikely
Quantitative Analysis
n/a
Current Status
COSEWIC: Special Concern (November 2007) [G4, S3, Blue-listed (BC) S2 (Idaho and Montana)]
Status and Reasons for Designation
Status: Special Concern
Criteria: not applicable
Reasons for Designation: The species has a restricted range in southeastern British Columbia and a limited area of occupancy. It is highly dependent on moist, shaded, faulted, rock outcrops, which are scattered throughout the otherwise dry landscape of the Southern Columbia Mountains. The climate in this region, which is characterized by extremes in temperature and humidity levels, compounds the isolated nature of the populations. This species’ highly specialized habitat requirements and life history increase its vulnerability to habitat disturbance and fragmentation. Road construction and small-scale hydro development are potential threats.
Applicability of Criteria
- Criterion A: Not applicable. No quantitative estimates of decline available.
- Criterion B: Not applicable. Although Area of Occupancy is less than 2,000 km², there are many more than 10 known localities, the range is not severely fragmented and there are not extreme fluctuations in range or abundance
- Criterion C: Given the uncertainties involved in estimating total population size and current knowledge of the number of localities, it is possible that there are more than 10,000 individuals.
- Criterion D: Not applicable. Area of Occupancy exceeds 20 km² and there are probably more than 1,000 mature individuals.
- Criterion E: Not applicable. Insufficient data.
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