Grizzly bear and human interaction in Yellowstone National Park : bear management areas

Abstract

In 1982 Yellowstone National Park, WY, USA created a Bear Management Area (BMA) program. The objective of the BMA program was to minimize human-bear conflict by separating bears from people in areas of the Park where overlap may occur. This was accomplished primarily through area closures, trail closures, and backcountry campsite closures. Our objective was to evaluate the interaction between grizzly bears and people and use the results to test the effectiveness of the BMA program. From 2007 to 2009, we obtained fine scale human and grizzly bear GPS data in 6 of 16 BMAs. To determine how grizzly bears responded to close interactions with people, we evaluated the GPS locations of bears and people in close proximity. We found that bears consistently avoided human interaction and often showed an avoidance response to people at close distances. We also evaluated spatiotemporal patterns of bear and human movements during times when BMAs were restricted (closed to human use) and unrestricted (open to human use). Through the comparison of the two time periods we found that bears continued to avoid people on a large scale. Furthermore, a significant amount of overlap between people and bears would occur if BMA restrictions were not in place. We also evaluated the effectiveness of backcountry campsite closures by testing if grizzly bears were attracted to, or avoiding occupied backcountry camps. We found that grizzly bears were attracted to the location of backcountry campsites, however there was a strong avoidance when these sites were occupied by people. Finally, we evaluated the behavioral and activity adaptations of bears occupying areas frequently used by people. We found that bears were primarily more night active and less day active when near areas that humans use. In addition, we found that if BMA restrictions did not exist, we could expect overlap between bears and people when both were highly active. Overall, our results suggest that grizzly bears consistently avoid contact with humans and that the BMA program in Yellowstone National Park is effective at reducing human-bear overlap, potential conflict, and reducing displacement of bears by humans.