干旱区生态环境知识资源中心

Timber harvesting and oil and gas extraction create ecological change beyond just the footprint of the resource extraction. These activities also create a permanent network of roads that can have lasting effects on forest ecology. Grizzly bears (Ursus arctos) suffer higher mortality when in close proximity to roads, yet bears in the foothills of west-central Alberta, continue to use these high-risk areas. We examined the hypothesis that bears were not necessarily attracted to logging roads but that these roads were placed in habitats that bears preferred. Using a resource selection function, we examined patterns in road placement and identified areas that had characteristics similar to roaded habitats (henceforth road-like habitats). We then quantified grizzly bear response to roads and road-like habitats. Of the 30 bears sampled, we found that 17 selected areas closer to roads than random and 11 selected road-like habitats. Road-like habitats were selected by subadults and some adult females but were not a good predictor of adult male habitat selection. Seasonally, grizzly bears selected habitats closer to roads in spring and early summer but selected road-like habitats more in late summer and fall, indicating that bears may be attracted to disturbed habitats in spring and undisturbed habitats in fall. We conclude that roaded habitats were selected by some grizzly bears but road placement in low-elevation valleys alone does not account for the strong selection preference. Although road placement likely plays a role, other factors such as clearcut association with roads may compound the attractiveness of roaded habitats to grizzly bears. The tradeoff between mortality risk and high-quality forage near roads must be addressed to prevent these areas from acting as attractive sinks. (C) 2008 Elsevier B.V. All rights reserved.