Cœur d’Alene salamander COSEWIC assessment and status report: chapter 5

Habitat

Habitat requirements

In south-eastern British Columbia, Plethodon idahoensis is associated with incised and fractured bedrock or wet talus in conjunction with water. It is known from rock walls with seepages or streams flowing over them (14 of the 56 known occurrence sites), waterfall splash zones (24 of 56 sites), caves (1 of 56 sites), step-like streams with exposed bedrock (10 of 56 sites), avalanche paths (3 of 56 sites), and wet talus (4 of 56 sites). These environments occur in steep terrain where the bedrock is near the surface and/or the talus has fallen down a slope. Overstory vegetation at sites is highly variable, ranging from deciduous shrubs (on steep seepage sites and avalanches courses) to mixed coniferous forest, in young to mature structural stages.

In south-eastern British Columbia, winters are cold and summers dry (Braumandl and Curran 1992). Whereas other western species of plethodontid salamanders, such as the western red-backed salamander (P. vehiculum) and the wandering salamander (Aneides vagrans) occupy deep, wet soils and downed logs of the humid coastal forest (K. Ovaska 1987, Davis 1998), soils in much of the range of P. idahoensis are shallow with limited leaf litter, and logs may remain dry even during extended rainy periods. In this harsh environment, the cracks in the bedrock provide refuge both from freezing and from desiccation for P. idahoensis, which may spend up to seven months of the year underground in moist interstitial spaces between rocks (Cassirer et al. 1994). Such deep rock retreats are vital to certain salamanders during extreme cold weather. The Appalachian species, P. dorsalis and P. richmondi; can survive extreme cold in areas that have talus and rocky substrates with numerous underground passageways (Petranka 1979). The structure and extent of underground retreats, although a vital, potentially limiting component of the habitat requirements of P. idahoensis, remain unknown. Interstitial spaces, portals from this subterranean environment to the surface, and conduits of moisture below the surface must all be important factors.

Habitat trends

Plethodon idahoensis habitat in British Columbia is generally in steep terrain where access is difficult. Highway widening and maintenance, however, will likely impact over 20 P. idahoensis sites that are partly in highway right-of ways, thus resulting in losses of habitat.

Habitat protection/ownership

Of the 56 confirmed occurrence sites, 31 have some degree of protection. Twenty-seven have been designated Wildlife Habitat Areas for P. idahoensis under the provincial Forest and Range Practices Act and 4 more are under consideration for this status (Identified Wildlife Management Strategy 2004). One site is on property managed by the Columbia Basin Fish and Wildlife Compensation Program (CBFWCP), 2 sites are in Mt. Revelstoke National Park (Dykstra 2004) and 1 is in Syringa Creek Provincial Park. Of the remaining sites, three are on private land, six on highway rights-of-way, and one at a Ministry of Transportation and Highways Rest Area. Two sites span both private land and highway rights-of-way, and nine span both crown land and highway rights-of-way.

There is an inherent bias in the number of reported occurrence sites that are adjacent to highway rights-of-way; safety and access concerns in steep terrain during nocturnal surveys resulted in a tendency to sample roadside habitats preferentially. Additional sites likely occur upslope on many watercourses, away from the road. Similarly, there are likely more sites on private land that was not accessed.

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