HABITAT USE BY MUSKOXEN (OVIBOS-MOSCHATUS) IN WINTER IN AN ALPINE ENVIRONMENT

Muskoxen (Ovibos moschatus) were introduced into a relatively snow-ric h alpine environment in Norway far outside their natural polar distrib ution 40 years ago. Habitat choice in winter by the muskoxen was compa red with topographical characteristics and snow and vegetation distrib utions. The density of fecal-pellet groups was approximately 1500/ha i n the exclusively used Dryas heath, more than 30 times greater than th at observed in the only two other heath communities, lichen heath and Juncus heath. Juncus heath had a standing graminoid biomass of ca. 30 g/m(2), but 50-60 cm of hard snow. Lichen heath had shallow snow (<40 cm) and low graminoid biomass (<4 g/m(2)) and was used primarily for r esting and rumination. Muskoxen clearly selected Dryas heath on calcar eous rock located on very steep slopes (>27 degrees), which offered th e only available areas with shallow snow (ca. 20 cm) and available gra minoids (ca. 10 g/m(2)) ''integrated ram hardness'' values were <200 k g cm in Dryas heath compared with 1500-2500 kg cm in the only other tw o heath communities. Dryas heath occupied ca. 1% of the entire study a rea, but was used intensively by muskoxen. A strong preference for ver y steep slopes with shallow snow indicates that muskoxen show little p lasticity in adapting to more snow-rich environments.