The muskox has always impressed me because it seems to come straight from prehistory. Its thick woolly fleece protects it from the harsh climatic conditions present most of the year in its environment.
The Dall sheep, photographed here mainly in Denali Park in Alaska, is the northernmost subspecies with an almost pure white coat. The consequences of global warming observed in Denali show that its habitat is increasingly shrinking, as shrub vegetation advances to higher elevations.