Warmer Temperatures Threaten Grizzly Food

Louisa Willcox wistfully recalls the day she and three friends were hiking in Wyoming, not far from Yellowstone, when they stumbled upon a giant whitebark pine. Encircling it with their arms, the three friends could barely reach one another’s fingertips. It occurred to Willcox, who directs NRDC's wild bears project, that this 1,000-year-old tree might once have served as a resting place for Sheepeater Indians, and that its cones have nourished countless grizzly bears. Its seeds have been collected and stashed away by Clark's nutcrackers (pictured above) across the region, providing sustenance through the harsh winter. Today, global warming has already begun to upend all of that.

Some experts predict the whitebark may be nearly extinct in Yellowstone within the next seven to ten years. The culprit? A tiny bug called the mountain pine beetle. Warming trends in the Northwest have allowed the insect to infest areas that were once far too cold for its survival.

Willcox began working with scientists to collect data on pine beetle infestations because the demise of the whitebark pine could directly affect the Yellowstone grizzly population. Grizzly bears, particularly sows, rely heavily on the high-fat whitebark seeds during the feeding frenzy before hibernation, and scientists have found a direct correlation between caloric intake and grizzly birth rates. With decreasing numbers of whitebark pine, experts worry that Yellowstone’s grizzlies will be forced to lower elevations in search of alternative food sources, leading them into areas of human habitation where they are at greater risk of being killed.

Although the Interior Department removed the grizzly bear from the endangered species list last year, it didn’t take into account the threat to the species posed by global warming and the pine beetle. NRDC has filed suit against the agency and at the same time has begun working with outdoor educators and guides to track the spread of beetle infestations throughout the region.