Elk,Mule Deer, and Cattle Foraging Relationships on Foothill and Mountain Rangeland

摘要

Foraging niche overlap among Rocky Mountain elk Cervus elaphus nelsoni; Rocky Mountain mule deer Odocoileus hemionus hemionus; and cattle Bos taurus was studied for 2 years on 37 000 ha of nonforested foothill and mountain habitat in northwestern Wyoming; Microhistological analysis was used to quantify botanical composition of ungulate diets from monthly fecal collections. Feeding habitat use was determined through monthly surveys from fixed-wing aircraft to record nonsolitary animals in nonforested habitat; Kulcyznski's similarity index was used to calculate dietary and feeding habitat overlap among the 3 ungulates; and these 2 indices were multiplied together to estimate foraging niche overlap. In all seasons; elk and cattle consumed grass-dominated diets mean = 61% and 81%; respectively; although elk diets were more diverse. Mule deer consumed more forbs and shrubs than either elk or cattle P < 0.10. Foraging niche overlap was high 45% between mule deer and elk in spring; Cattle in summer and fall had >60% foraging niche overlap with elk in spring; indicating that; in spring; elk foraged in many of the same places largely sagebrush grassland and ate diets similar in botanical composition to what cattle did during summer and fall principally Festuca idahoensis; Pseudoroegneria spicata; and Achnatberum spp.; Foraging niche overlap also was high 41%-.S1% between elk in winter and cattle in summer and fall. Therefore; if competitive or complementary relationships existed betweenelk and cattle; these interactions most likely occurred on sagebrush grasslands where cattle use in summer-fall was followed by elk use in winter-spring. We recommend that resource managers focus their forage utilization and range trend monitoring in foothill sagebrush grasslands.