MULE DEER AND ELK FORAGING PREFERENCE FOR 4 SAGE-BRUSH TAXA

A 10 year study under natural winter conditions at 2 sites tested the hypothesis that mule deer (Odocoileus hemionus hemionus) and elk (Cerv us elaphus nelsoni) forage equally on 4 sagebrush (Artemisia L.) taxa, Each year approximately 2,500 available leaders on 244 plants on the Northern Yellowstone Winter Range were examined for browsing, Browsing levels increased with winter severity, reaching 91% of leaders browse d for mountain big sagebrush (A. tridentata ssp, vaseyana [Rydb.] Beet le), the preferred taxon (P less than or equal to 0.05) that averaged 56.1% at the 2 sites, Wyoming big sagebrush (A.t. ssp, wyomingensis Be etle and Young) was narrowly preferred (38.6%) over basin big sagebrus h (A.t. Nutt, ssp, tridentata) (30.3%), Black sagebrush (A, nova Nels. ) was least preferred (17.0%), Differences in preference among taxa we re smallest during the severest winters when more elk were present the reby increasing total sagebrush utilization, Mule deer diets averaged 52% sagebrush over the study, Many sagebrush plants were damaged and e ven killed by heavy browsing during the study, Promoting sagebrush pro ductivity should be a management objective on similar winter game rang es.