The Roosevelt elk (Cervus canadensis roosevelti) is very similar to the Rocky Mt. form in both life history and physical characteristics, but the Roosevelt form is somewhat larger and heavier. Breeding occurs Sept. 15-Oct. 15; harems consist of 5 to 15 [female][female], calving May 15 to June 15. Mature bulls are isolated from [female][female] except during the breeding season. Elk return to the same wintering ranges each season; they browse during winter, graze and browse remainder of season; the principal browse spp. are vine maple, huckleberry, salmon-berry, but western hemlock, western red cedar, Douglas fir, and Sitka spruce are much used. The West side peninsula produces the most elk. Of 7049 elk identified as to sex, 70% were adult cows, 20% were calves, 6% were adult bulls, 4% were spike bulls; 43% of the adult cows were breeding. 112 elk were found dead; the heaviest losses were in 1937. Malnutrition was the principal cause. Usual infections are lung worms, tape worms, intestinal worms, bot flies, ticks and lice. Cougar, coyote and bobcat are the principal predators. Hunting had only slight effect on population but changed the take of 6-point bulls from 30% in 1936 to 15% in 1939.