Characteristics of Habitat for Mountain Sheep

I describe habitat components for mountain sheep (bighorn [ Ovis canadensis ], thinhorn [ Ovis dalli ]) in North America. Habitat characteristics for mountain sheep vary between subspecies, sex and age groups, life stages, occupied habitat, predators, livestock, and anthropogenic activity. The use of rugged terrain is a universal characteristic of mountain sheep habitat that is intertwined with all aspects of their habitat. Escape terrain is rugged habitat where sheep can avoid predation, and sheep are rarely far from it. Escape terrain for thinhorn sheep usually includes rock complexes and bluffs with limited snow. Thermal cover is important as shade in summer and increased solar radiation in winter for bighorn sheep. Thinhorn sheep are in much colder areas than bighorns and rely on areas with increased solar radiation, sheltering terrain, vegetative cover, and high wind speeds to remove snow from forage. Lambing areas are related to escape terrain and occur in rugged areas intermixed with forage, but with desirable southerly aspects. Lambing habitat is only used during a short period of the year, but the value of the areas cannot be understated with respect to lamb production. Water is an important habitat feature for all mountain sheep but is readily available within the habitats of thinhorn sheep and is not a limiting factor in most seasons or years. In arid areas of bighorn habitat water can be obtained from surface water or vegetation, but for many populations of desert bighorn sheep, water is a limiting factor. Forage and foraging areas are also important for mountain sheep. The types of plants used and available may not be as important as the horizontal visibility. Mountain sheep generally avoid areas where their vision is restricted. There is still more to be learned about the habitat of mountain sheep, especially in isolated populations and local ranges.