Weather, Water, and Precipitation

Mountain sheep (bighorn sheep [ Ovis canadensis ], thinhorn sheep [ Ovis dalli ]) occupy ranges with extreme seasonal climatic conditions, ranging from high temperatures and limited surface water for desert bighorn sheep ( O. canadensis spp.), to northern bighorn and thinhorn ranges, characterized by extreme cold and snowy winter conditions. These conditions pose physiological challenges and mountain sheep use behavioral, physiological, and morphological adaptations to maintain temperature and water balance. Mountain sheep meet water requirements from free-standing water, forage moisture content, and metabolic water produced during the oxidation of fats, carbohydrates, and proteins. Survival, reproduction, and population dynamics of mountain sheep are also influenced by climatic conditions. Poor forage associated with dry conditions can result in higher mortality rates and lower lamb recruitment in desert bighorn sheep and extreme winter weather can influence survival, reproduction, and population growth of northern bighorn and thinhorn sheep populations. Extreme weather events, such as droughts, heavy snowfall, and storms, can have immediate and severe influences on mountain sheep populations.