Bighorn sheep and Elk Valley coal mines : ecology and winter range assessment Poole, Kim G.; Smyth, Clint R.; Teske, Irene; Podrasky, Kevin; Serrouya, Robert; Sword, Greg; Amos, Lanny
Rocky Mountain bighorn sheep inhabit the east side of the Elk Valley in southeastern British Columbia where forestry and 4 large, open pit coal mines are in operation. Sheep in this area generally winter at high elevation on windswept, south facing native grasslands, with some sheep also wintering on mine properties. Concurrent companion studies examined sheep habitat ecology and movements; and winter range plant communities and production, range condition, and winter diet. We monitored 41 ewes and rams over 26 months using GPS-collars. Most of the sheep monitored were seasonally migratory (79%) and showed high fidelity to winter ranges among years (88%). Use of mine properties varied seasonally, from ~10-18% during winter to peak at about 60-65% during autumn. Ewes lambed both in natural habitats and on mine properties. Fifteen winter ranges were identified, which in native habitats were typically a complex of grasslands, shrub lands, vegetated and non-vegetated rock outcrops, and cliffs. Sampling of these ranges found that standing crop production was highest in ranges with the greatest percentage cover of graminoids often dominated by rough fescue and where productive soils were prominent. High use by elk was observed on many of the ranges. Grazing was greatest on productive sites; sheep utilization declined with increasing distance from escape terrain. Three of the winter ranges are considered to be unhealthy ecologically.
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