Bears in Models and in Reality: Implications to Management

Abstract

The use of computer simulation models as an aid to understanding of biological data was demonstrated using a number of simulated bear populations. Data from black (Ursus americanus), brown (U. arctos), and polar bear (U. maritimus) populations were employed. Population models without feedback were used to compute mortality isoclines as a function of reproductive measures and to document the unreliability of age structure as an indicator of population growth form. A simple Leslie matrix projection was modified to include the effects of population density and hunting. The resulting models provided a consistent explanation for some of the sex and age ratios reported in the literature. The importance of spatial and temporal distributions of hunting pressure were documented, and management implications of hunting patterns, population biology, and dispersion of bears were summarized. Of the enormous amount of detail known about bears, not all is amenable to simulation modeling; similarly, not all modeling techniques are appropriate to simulation of bear biology. Here we deal with the intersection of bears in models and reality. Our scope is broad taxonomically but narrow ecologically. We pre? sent analyses of black, brown, and polar bear popula? tions but limit ourselves largely to the examination of population dynamics. Analyses are extended to en- compass some relations with habitat through the influ? ences of habitat on man as hunter. We limit our discus? sion largely to the simplest forms of models, those adapting the Leslie matrix formulation without feed-