0 Mills, Harlow B. 1937 Journal of Mammalogy American Society of Mammalogists 18 205-212 May, 1937 animal studies, behavior, bighorn sheep (Ovis canadensis), disease, habitats, mammals, migration, pellets (fecal), population, range, reproduction, wildlife health, general wildlife health studies, Rocky Mountain Bighorn Sheep For many years the condition of the bighorn, Ovis canadensis canadensis, in Yellowstone National Park has not been favorable. Although the animals have been rigidly protected, and their natural enemies are not so abundant in the Park as formerly, their numbers, according to estimates, have remained quite continuously around the 200 mark. This static condition cannot be due to dearth of range, for Bailey (Animal Life of Yellowstone National Park, 1930) suggested that there may be range in the Park for 2000 animals without encroachment on that of other game animals. With the object of attempting to discover the adverse factors affecting the bighorn, studies were carried on throughout the winter of 1934 and 1935 under the direction of the Wildlife Division of the National Park Service. During the 9 months that these studies were prosecuted, a considerable amount of biological data has accrued. The purpose of this paper is to present some of these data, together with some conclusions which have been reached. Found online, pdf on computerNatureBib ID: 97151 http://links.jstor.org/sici?sici=0022-2372%28193705%2918%3A2%3C205%3AAPSOTB%3E2.0.CO%3B2-P