CRAIG K. LORENZ / SCIENCE PHOTO LIBRARY CRAIG K. LORENZ / SCIENCE PHOTO LIBRARY
Rocky Mountain Elk (Cervus elaphus nelsoni) harem bull in full rut. To be dominant, a bull must be big, strong, and in his prime, from 5 to 12 years old. A bull's antlers tell much of his story. Bulls in their prime have the largest, most magnificent antlers. Other male and female elk measure the physical worth, and to a certain extent, the behavioral worth, of a bull by looking at his antlers. Rocky Mountain National Park, Colorado.
Model release not required. Property release not required.