Figure 12.21 A static life table and survival rate curve for Dall sheep. Using the ages of Dall sheep skeletons found in Alaska, researchers calculated the survival and survivorship of different age classes. When graphed, these data show that the survival rate of the sheep remains quite high for the first 7 years and then rapidly declines. There were only four animals in the 12-year age class and this resulted in an unreliable high estimate of survival rate.

Based on data from O. Murie, The Wolves of Mt. McKinley (U.S. Department of the Interior, National Park Service, Fauna Series No. 5, Washington, D.C., 1944), as quoted by E. S. Deevey, Jr., Life tables of natural populations of animals, Quarterly Review of Biology 22 (1947): 223–314.