Dietary niche relationships among cervids relative to winter snowpack in northwestern Montana

Abstract

We compared diets of white-tailed deer (Odocoileus virginianus ochrourus), Rocky Mountain elk (Cervus elaphus nelsoni), and Shiras moose (Alces alces shirasi) during two winters in the North Fork of the Flathead Valley, Montana. Diets of white-tailed deer contained the greatest proportions of low-lying evergreen shrubs, as well as high proportions of coniferous browse. Elk selected greater proportions of grasses than did white-tailed deer or moose, whereas moose consumed the greatest proportion of deciduous shrubs. Deep snow in 1982 increased the similarity of diets chosen by white-tailed deer, elk, and moose. In 1982, white-tailed deer and elk consumed more total browse, and moose more coniferous browse, as deep snow covered the preferred forages. Increased dietary overlap and energy limitations suggested a potential for interspecific competition during harsh winters.