SURVIVAL RATES REQUIRED TO SUSTAIN BEAR POPULATIONS

A simple approximation to the Lotka equations permits using various combinations of population dynamics parameters to determine adult female survival rates needed to sustain a constant population level under various conditions suggested by observed data on grizzly (Ursus arctos) and polar bears (U. maritimus). The approximation should be useful in evaluating more complex models. Data on polar bears illustrate a method for estimating the ratio of early survival rates to that for adults. Such a ratio may be useful in establishing appropriate combinations of subadult and total adult survivorship for sustained population levels. -Author