The influence of variable snowpacks on habitat use by mountain caribou

Rangifer 01/2010; 27(4). DOI: 10.7557/
Source: DOAJ


Mountain caribou (Rangifer tarandus caribou) in southeastern British Columbia subsist for most of the winter on arboreal hair lichen, mostly Bryoria spp. Foraging occurs mainly in old subalpine fir (Abies lasiocarpa) forests near treeline. Here, the lower limit of Bryoria in the canopy is dictated by snowpack depth because hair lichens die when buried in snow. Bryoria is often beyond the reach of caribou in early winter, prompting caribou to move downslope to where lichen occurs lower in the canopy and other foraging modes are possible. Snowpacks are normally deep enough by late winter that caribou can reach Bryoria where it is most abundant, at high elevations. Extending this to inter-annual comparisons, Bryoria should be less accessible during late winter of low-snow years following normal winters, or of normal to low-snow years after deep-snow winters. We hypothesized that when maximum snowpack in late winter is low relative to the deepest of the previous 5 years, mountain caribou will use lower elevations to facilitate foraging (“lichen-snow-caribou” or LSC hypothesis). We tested this with late-winter data from 13 subpopulations. In the dry climatic region generally and for minor snowfall differences in wet and very wet regions, caribou did not shift downslope or in fact were at higher elevations during relatively low-snow years, possibly reflecting the ease of locomotion. The LSC hypothesis was supported within wet and very wet regions when snowpacks were about 1 m or more lower than in recent years. Elevation declined by 300 m (median) to 600 m (25th percentile) for snowpack differences of at least 1.5 m. Greater use of lodgepole pine and western hemlock stands sometimes also occurred. Management strategies emphasizing subalpine fir stands near treeline should be re-examined to ensure protection of a broader range of winter habitats used by caribou under variable snowpack conditions.

Download full-text


Available from: Bruce Mclellan
  • Source
    • "Grazers are especially sensitive to snow (Robinson and Merrill 2012), whilst mixed-feeders (e.g. grazing and browsing) often show shifts in food selection, as reported in mountain caribou (Rangifer tarandus caribou) (Kinley et al. 2007). Second, the hardness and density of the snow cover influence the sinking depth of the animals in the snow (Lundmark and Ball 2008), increasing the energetic cost of walking (Parker et al. 1984; Bunnell et al. 1990) and ultimately leading herbivores to decrease mobility and overall activity (Rivrud et al. 2010), especially in small and medium species (Telfer and Kelsall 1984; Mysterud et al. 1999). "
    [Show abstract] [Hide abstract]
    ABSTRACT: In alpine environments, snow typically reduces the accessibility of herbivores to food during winter and may hamper survival in those species with poor adaptation to move in deep snow. Supplemental feeding systems compensate for food limitation, but modify resource distribution and potentially affect individual space use. We investigated the importance of snow cover and supplemental feeding in shaping winter habitat use and selection of the European roe deer (Capreolus capreolus), a small deer species not specifically adapted to snow. We applied a used/available experimental design to assess the effects of snow cover on roe deer distribution at a fine scale and compared this approach with remotely sensed satellite data, available at moderate spatial resolution (snow MODIS). Based on this, we developed a resource selection function. We found a strong selection for habitat spots covered by forest where snow sinking depth was less pronounced, likely providing thermal and hiding protection on the one side and minimising the effect of snow on locomotion on the other. Roe deer showed only a minor preference for sites in proximity to feeding stations, possibly compensating the costs of access to these sites by means of a ‘trail-making’ behaviour. Snow cover assessed by moderate resolution satellite was not proportional to roe deer probability of use, highlighting the importance of local information on snow quality and distribution to complement remotely sensed data.
    Full-text · Article · Feb 2015 · European Journal of Wildlife Research
  • Source

    Preview · Article · Jan 2008
  • [Show abstract] [Hide abstract]
    ABSTRACT: On the windward slopes of the Columbia and Rocky Mountains is a 7 million-hectare disjunct rainforest (see figure 3-1) that arguably includes the largest expanse of inland temperate and boreal rainforests on Earth (but also see Inland Southern Siberia, chapter 9). Most rainforests here are temperate except at the most northerly latitudes, where they grade to boreal rainforest. Although early biogeographers noted the unexpected presence here of numerous species typical of coastal regions (e.g., Daubenmire 1943), only recently have ecologists recognized these forests as a distinct entity: an inland counterpart to coastal rainforests of the Pacific Northwest (Alaback et al. 2000; Goward and Arsenault 2000; Goward and Spribille 2005).
    No preview · Chapter · Sep 2011
Show more