Demography and habitat selection by grizzly bears (Ursus arctos L.) in central British Columbia.

摘要

I conducted a radiotelemetry study of grizzly bears (Ursus arctos L.) near the Parsnip River, British Columbia, 1998-2003. Prior to this study there have been no scientific investigations of grizzly bears inhabiting BC's Arctic watershed. Further, the link between changes in the land base created by forestry activities and grizzly bear habitat selection was lacking. In this thesis, I examine and model factors that contribute to the 4-fold higher density of bears in a relatively pristine mountainous landscape than in an adjacent plateau that has been heavily harvested for timber. To determine genetic differentiation, migration, body weight and condition, reproductive parameters, annual survival rates, mortality, multi-scale habitat use, and den-site selection, I radiotracked up to 59 grizzly bears, visited bear-use locations, and used 15 loci microsatellite markers for 133 individuals. I used resource selection functions (RSF) to estimate the relative probability of use during foraging and denning seasons. DNA-based estimates of population size were used to apply new methods for linking populations to habitats by scaling RSF models to density.; In contrast with the findings of studies where grizzly bears fed upon salmon, I found that during the foraging season bears selected for early seral habitats created by forestry operations. Results suggest that plateau bears were not limited by available forage based on their heavier weight, superior condition, and high cub survival rate. Rather, 3 main factors contributed to low population density on the plateau: (1) no female, and limited male, migration of bears from the mountains; (2) increased human access via high road densities; and (3) use of areas where human-caused mortality was high. Forestry operations increased human access while creating early seral habitats, making these areas an "attractive sink" for bears. Habitat selection was scale dependent; results varied between mountain and plateau landscapes, males and females, and across scales. Management recommendations included restoration through road closures and reclamations on managed landscapes, and altering future timber harvest plans to minimize the need for permanent roads. Legal kills can be controlled through permits and restricting human-access; however, reducing illegal kills will require increased hunter education, access management, and law enforcement.