Snow Depths and Ungulate Abundance in the Mountains of Western Canada

Abstract

It is long established that winters, or 'hard winters, cause fluctuations in ungulate populations. Annual reports of the British Columbia Game Department have noted since 1912 that such winters may cause serious declines. Roe (1951) reports hunters' traditions as early as 1875 attributing bison decreases on the American prairies to severe winters. Published accounts of ungulate mortality due to severe winters or deep snow involve a wide range of species in a large geographic area. Holzworth (1930: 23) notes that blacktailed deer on the islands of southern Alaska die in thousands during severe winters. Spiker (1933) considers deep snow as the only important factor in winter mortality of Adirondack white-tails. Rand (1947) concludes that severe winters with deep snow are the worst enemy of pronghorn antelope in Alberta. Murie (1944) records heavy losses in Dall sheep, and in moose, during severe winters with deep snow in Alaska. Roe (1951) quotes numerous historic references describing American bison declines because of snow, but discredits most of them in support of his thesis that man, not snow, was the bison's chief enemy. Cowan (1950) records a cold winter with deep snow that reduced mountain goat survival in the Canadian Rockies, and later (1952) calls winter the greatest enemy of goats. The latter paper also postulates the near extermination of elk in the Rocky Mountain region as a result of severe winters in the 1870's and in