Modeling the effects of harvesting on black bears in the Southern Appalachians

The black bear (Ursus americanus) population of the southern Appalachians is one of the most dense in North America. As a result, during fall mast failures an increasing number of nuisance bears may leave Great Smoky Mountains National Park and the surrounding national forest boundaries and enter human-populated areas. I developed two models to address several problems regarding this population: a metapopulation harvesting model and a spatially-explicit individual-based model. The metapopulation model involved a coupled set of logistic-type growth models that included density-dependent immigration and emigration and harvesting. I applied Pontryagin 's Maximum Principle to derive an optimal harvesting and reserve design strategy for the system. Model results suggested that a forest region's population could be maintained despite high harvest levels because of emigration from a connected, unharvested park region. The amount of shared border between the park and forest region was important in determining the optimal harvesting strategy. The individual-based model used geographic information system ( GIS) map layers of human density, bear sanctuaries and forest type to model the system. The model suggested that fall mast failures had a two-fold effect on the population. First, the lack of food caused bears to emigrate into unprotected areas and second, the Jack of food caused females to enter denning with low caloric reserves. This resulted in high cub mortality. Various alternative harvesting scenarios were tested to determine the best harvesting regime and reserve design strategy for minimizing potential bear-human encounters and maintaining the population. The model provides the ability to analyze spatial rearrangements of sanctuaries in addition to alternative harvesting regulations.