Which curve best fits ground squirrels?
Ground squirrels are commonly represented by a Type II survivorship curve because their probability of dying is treated as approximately constant across much of life. On a semilogarithmic survivorship graph, a constant hazard produces a roughly straight decline. Real populations can depart from this ideal when juveniles, dispersers, or old individuals experience different risks, so the classification is a broad empirical approximation. A survivorship curve is built from a cohort life table by plotting the proportion alive at each age. Type I concentrates mortality late, Type II approximates a
Ref: Ecology: Concepts and Applications, Molles, 9th Ed., Ch. 12