Landscape-scale connectivity, which allows animals to move within ecosystems and exchange genes with outside populations, is a crucial component of carnivore recovery and conservation.
Transportation corridors characterized by high road densities and substantial vehicle traffic can result in “fracture zones” that are detrimental to carnivore populations because they increase mortality (e.g., wildlife-vehicle collisions) and inhibit natural patterns of animal movement. Washington’s North Cascades Ecosystem (NCE) is traversed by three east-west highways: I-90, US Route 2, and State Highway 20 (see Where We Work).
In 2008, the Western Transportation Institute and the Okanogan-Wenatchee National Forest launched the Cascades Carnivore Connectivity Project to help evaluate and advance habitat connectivity for carnivores in Washington’s NCE. Using noninvasive genetic data, we are employing a suite of population and landscape genetic approaches to evaluate the effects of I-90, Route 2, and Highway 20 on carnivore populations across the region (see Research Objectives).
Pilot surveys were conducted in 2008. American black bears, American martens, and bobcats were originally selected as focal species, with bobcats having since been dropped from the list due to sampling challenges. Building on our pilot research, we developed a three-year, landscape genetics study (see Methods) to assess the barrier effects of major highways on black bears and martens. This study is scheduled for completion in 2012.
In 2010, we also became involved in a broader initiative to survey for grizzly bears in Washington’s NCE as part of the US Fish and Wildlife Service’s long-term recovery planning process for this species (see Grizzly Bear Survey).