De Fragmenting the West: Providing Adaptive Options for Grizzly Bears to Respond to Climate Change
Time: 12:00-1:30 PM Mountain Time
Presenters: Michael Proctor, Trans-border Grizzly Bear Project and Chris Servheen, US Fish & Wildlife Service
Population fragmentation compromises population viability, reduces species’ ability to respond to climate change, and ultimately reduces biodiversity. It is predicted that climate change will exacerbate existing fragmentation, and that fragmentation will further challenge species’ abilities to adapt. Using genetic samples from 3,143 bears and telemetry for 792 bears, we documented extensive population fragmentation of grizzly bear populations in northern US, Alberta, and British Columbia, Canada. Using individual-based analyses we determined real time inter-population movement rates illustrating current conditions. We found several small (less than 100 bears) and therefore threatened subpopulations and larger core subpopulations (greater than 500 bears). We further demonstrated the likely causes of this fragmentation as being patterns of human settlement, highway traffic, and human-caused mortality (historic and recent).
While reduced male grizzly bear movements mediate gene flow, minimal female movements challenge any natural augmentation or demographic rescue if required. The long-term persistence of this system, including small threatened subunits, will require connectivity-oriented management. We used more than 50,000 locations from GPS telemetry of 31 bears in the trans-border region and habitat modeling to identify core and linkage habitat across 9 highway and settlement corridors in the Purcell, Selkirk, and Cabinet Mountains between Missoula, Montana and Revelstoke, BC. We evaluated our models and selection of linkage habitat using independent data. We discuss our efforts to facilitate private land purchases, conservation easements, public education, and other management actions on public lands to secure these linkage areas for movement of wildlife.