Science Story

What Happens to Lynx When Beetles Eat the Forests?

Rocky Mountain Research Station
February 5th, 2016 at 6:00AM

Canada lynx kitten born of a female that denned in spruce beetle impacted forests in 2015, Rio Grande National Forest, CO  How does a sensitive species like Canada lynx adapt to large areas of beetle-killed forest?  Where do you start?  A great choice would be with John Squires, a research wildlife biologist with the USDA Forest Service’s Rocky Mountain Research Station in Missoula, Montana.  John began studying lynx in1997, when many of the aspects of their ecology were unknown.  His study results have helped land managers sustain lynx populations in areas of multiple uses.  Now John leads a research team responsible for finding what’s needed to conserve threatened, endangered, and sensitive forest carnivores throughout the Rocky Mountains.

So, when the wildlife biologist on the Rio Grande National Forest in southwestern Colorado needed a lynx expert, he called John, (see the article in the Pueblo Chieftain).  When Colorado state wildlife officials began introducing Canada lynx into the San Juan Mountains in 1999, a few years before a massive spruce-bark beetle outbreak, they were releasing the cats into the best available habitat in the state.  By 2013, the beetle infestation had affected 85% of the mature spruce-fir forests on the Rio Grande.  Now, Forest officials are trying to salvage log the dead stands without harming the cat, currently listed as threatened under the Endangered Species Act.

John, in cooperation with Rio Grande National Forest, Region 2-U.S. Forest Service, Colorado Parks and Wildlife, and Montana State University, is directing a mapping study of collared cats on the Forest, plotting points in and around the cats’ home ranges in different vegetation types.  This study requires an accurate map of forest conditions in beetle-impacted forests, so Dr. Rick Lawrence and Dr. Shannon Savage, Spatial Sciences Center at Montana State University, are building models of forest conditions based on vegetation field data collected last summer.  John and his team will use this map and other data sources to build computer models that predict how lynx will use other sections of beetle-impacted forest on the Rio Grande.  “That way you could, if you’re a manager, try to say, ‘OK, these areas are more important for lynx, these areas are more important for salvage’ and try to balance the multiple use in a way that serves conservation and serves forest management, too,” John said.

Spruce-fir affected forests from spruce bark beetle in Canada Lynx habitat, Rio Grande National Forest, CO

A second related study led by Dr. Jake Ivan, Colorado Parks and Wildlife, examines how the lynx’s primary prey source, the snowshoe hare, is faring with the beetle outbreak.  Both studies have little research to build on, thus providing a unique opportunity.  “This is probably right now the only place in the continental United States that we can look at this issue because in Montana we don’t have these big areas of spruce-bark beetle impacted areas in lynx habitat,” John said.

There is hope for Colorado’s lynx.  The understory, important in providing shelter, food, and cover for the snowshoe hare, is regenerating.  Two of the collared cats have had kittens in the area.  And, maybe most encouraging, the lynx have not changed their home ranges.  In the northern U.S., research has found lynx populations make long journeys when the hare populations decline.  That doesn’t hold true for this population.  “These animals are actually living in a normal-sized home range – and denned in it,” John said.  “I think that’s also encouraging.”

Stay tuned for a documentary featuring this research.  A BBC film crew for the new series, “The Story of Cats,” recently spent time with John and his team on the Rio Grande.