| I studied the relationships among black bears, roads, and habitat at two study areas (east-side and west-side) in the North Cascades by using radio-telemetry from 1995–1998. Compositional analysis showed that black bear activity levels were not equal across time periods and they exhibited crepuscular activity patterns regardless of sex, season, or study area. Monitoring of black bear denning chronology and site selection showed that male bears entered their dens between 22 October and 19 November and emerged between 4 April and 7 May. Females entered dens sooner, 15 October to 19 November, and emerged later than males, 4 April to 22 May. Roads influenced den site selection as bears used dens in areas with no open roads >200 ha in size, >500 m from the nearest open road, and 1500–2000 m in elevation. Resource use was assessed at the 2nd and 3rd orders of resource selection. At the 2nd and 3rd orders on the westside, compositional analysis ranked low-mid elevation conifer forests, deciduous forest, and areas with no open roads >40 ha in size as highly used. On the east-side, low-moderate elevation forest, deciduous forest, riparian, montane and subalpine/alpine meadows, and areas with no open roads or low road densities were ranked as highly used. On both study areas, high open road densities were consistently ranked as low use. I used logistic regression to derive scaled resource selection functions, and a habitat-based population model to evaluate habitat effectiveness and capability for female black bears. Roads reduced habitat effectiveness during all seasons at both study areas and changes in potential habitat values ranged from 1.7% to 16.9%. The greatest reduction occurred during the early-season on the west-side due to high open road densities. On the west-side, the potential black bear population size was most influenced by moderate use roads and timber harvest during the early-season (41% reduction). On the east-side, low use roads had the greatest effect on potential black bear population size during the early-season (10% reduction). This study supports the hypotheses that roads: (1) influence black bear den site selection, (2) influence where bears establish core use areas and home ranges, (3) reduce habitat effectiveness, and (4) reduce habitat capability. Roads could be managed to reduce open road densities and limit traffic volumes. |
