The Shiras moose, Alces alces shirasi, and its winter habitat on the north slopes of the Uinta Mountains in Utah were studied from August, 1969, to July, 1971 to determine the food requirement for moose, the key browse species during the winter months, the acreage, density and utilization of the key browse species, and their carrying capacity for moose. It was determined that an average adult moose had a daily food requirement of 19,133 kilocalories. The key browse species for moose were Salix drummondiana and S. geyeriana. These two species accounted for 92.0 and 4.7 percent respectively of all feeding occurrences on browse species recorded. According to density analyses, S. drummondiana made up 59 percent of the vegetation and S. geyeriana 31 percent. The caloric capacity of the key browse species for moose body maintenance was slightly more than 1.5 billion kilocalories. The moose carrying capacity of the key browse species on the winter range was 80,030 moose days or 445 adult animals for a period of six months. Specifically, the carrying capacity, based on a weighted caloric requirement and annual classification counts, would be 115 bulls, 250 cows, and 156 calves for a period of six months on the winter range.