Our link to the boreal
In-depth article on Canada lynx by wildlife biologist Gary Koehler
by Gary Koehler, wildlife research scientist, Washington Department of Fish and Wildlife
Washington hosts three species of wild felids: cougars (Puma concolor), bobcats (Lynx rufus), and Canada lynx (Lynx canadensis). Of these, the Canada lynx is unique because of their special requirements for habitat and prey.
Lynx are found throughout the boreal forests of Alaska and Canada but make a presence in the 48 contiguous states only near Canada’s border in Washington, Idaho, Montana, Minnesota, and Maine. Lynx have been reintroduced from northern Canada to Colorado’s mountains where they occurred historically.
Lynx are masters of deep snow and cold winters. In Washington, they are at home among the boreal habitats in Okanogan County, where winter persists for much of the year, and they have been best studied here. Lynx occasionally meander down from British Columbia into the spruce and subalpine fir forests of Ferry, Stevens, and Pend Oreille counties, but only Okanogan, as far as we know, has sustained populations for the past four to five decades or more.
Their down-like fur protects them from the cold, and their large paws (the size of a cougar’s foot) and small weight (similar to a 25-pound bobcat) enable lynx to float on the deep fluffy snows of the high elevations of northern Washington. These large feet act as snowshoes for lynx to pursue their primary prey, the snowshoe hare (Lepus americanus).
Lynx are specialist predators of hares, and their populations reflect the abundance of this one prey species. At northern latitudes, lynx populations fluctuate in response to hare abundance. However, here in Washington, where hare numbers remain relatively low and stable, lynx numbers are low, and their populations do not fluctuate as they do farther north. In the high elevations of Okanogan County, a township (1 square mile) of Engelmann spruce and subalpine fir forest may support a single male and perhaps a female or two. Numbers of hares also dictate the survival of lynx kittens. Born in early summer, litters of two or three kittens will accompany their mother until late the following winter, when their tracks can be seen alongside those of their mother in mid-winter snows.
Snowshoe hares prefer habitats where dense stands of conifers provide shelter from cold and predators and where they can forage on conifer bows that protrude above 3 feet of snow. These forest thickets may result from wildfires, other disturbances or when forests mature and the canopy thins to permit a succession of young trees and herbaceous plants. Large wildfires are a part of the dynamics of these boreal ecosystems. Replacing old stands with a succession of young forests results in hare proliferation and thriving lynx populations.
Although wildfires may be important in creating lynx habitat, the excessive numbers of fires in the past decade may be a threat to the species’ survival in Washington. In recent decades, the warmer summers and winters that scientist believe are coupled with climate change create conditions for insects to thrive. These high-elevation forests have experienced an epidemic of budworm and bark beetle throughout much of western US and Canada, with millions of acres of dead and dying trees creating conditions for high intensity large wildfires. In the past decade, more than 50 percent of these spruce and subalpine fir forests along the northeastern Cascades have been burned, with the 2006 175,000 acre Tripod Peak fire in the Okanogan being most notable.
In addition, we may have contributed to an abundance of forest fuels from nearly a century of fire suppression. This has dramatically changed things for lynx and a variety of species that inhabit these boreal forests. Together, these changes bode an uncertain future for lynx in Washington.
Historically, when large fires burned and habitat for hares and lynx was displaced in Washington, there was likely a reservoir in British Columbia from which lynx could emigrate and repopulate here. With the present scale of forest disease and large, high-intensity wildfires, it is uncertain whether BC can provide the refugium to rescue threatened lynx populations in Washington.
Diligent monitoring of forest conditions and our management activities will provide the information needed to adapt our management of these boreal landscapes and to continue to provide a home for the lynx and other species like the boreal chickadee and bog lemming in Washington. To avoid a strategy of not having all the lynx in one Okanogan “basket,” relocating lynx to northeastern Washington, the Kettle River Range for example, where they occurred historically should be considered. Collaborations with forest and wildlife managers in British Columbia are needed, for these boreal species do not recognize the 49 degree latitude as an ecological boundary.
The lynx and the boreal forests they occupy are a unique little patch of the Yukon in our own backyard. Will they survive the changes and challenges that are at their doorstep?