Bear Versus Beetle
On a clear day this past spring, Jesse Logan strapped on his backcountry skis and pushed into the whitebark pine forest that surrounds Montana's Emigrant Peak, a dramatic 10,900-foot mountain that rises from the idyllic Paradise Valley north of Yellowstone National Park. Armed with a GPS unit and an ax, Logan, a retired U.S. Forest Service research entomologist, went to tally the dead and search for survivors.
Over the past six years these forests have suffered unprecedented losses, turning vast expanses of the mountain landscape a rusty red. Global warming has ended the 40-below cold snaps that used to act as natural protection for the whitebark pine, which thrives above 8,500 feet. These low temperatures used to kill off the mountain pine beetle, a boring insect that can destroy a tree in a single season. Without them, beetle populations have exploded, decimating the whitebark pine, whose nuts are a crucial food source for grizzlies fattening up for winter.
Logan is helping to assemble a database and map that track the health of whitebark pine forests in the 20 million acres of the Greater Yellowstone Ecosystem. Fortunately, he's not alone. For the past 18 months, a small cadre of volunteer citizen scientists has been gathering data on whitebark pines. Outfitters, wilderness advocates, hikers, hunters, and mountain climbers are taking photographs and noting GPS locations of both healthy and infected stands.
"It's incredibly important data," says Wally Macfarlane, a geographic information systems specialist with the Utah-based company GEO/Graphics. Working with Logan and Louisa Willcox, director of the Natural Resources Defense Council's Wild Bears Project, Macfarlane is combining the data with Google Earth technology to produce a regionwide map. "The Forest Service tracks the beetle's spread through lodgepole pine forests because they're economically valuable trees for logging, but they don't track the whitebark pines," he says. "So it's up to us to go out and get the data."
To Yellowstone's grizzlies, which were taken off the endangered species list last year, there is no more important food source. The bears don't climb the trees to reach the nuts, but squirrels do and then bury them in the ground. In late summer and early fall, grizzlies break open the squirrel caches and gorge themselves on the high-fat nuts. "Female grizzlies with more winter fat have more cubs," Willcox says.
Entering the data gathered by the citizen scientists into a complete regionwide map could be crucial to the survival of the Yellowstone grizzly population. The bear's delisting, which has been challenged in a federal lawsuit brought by a number of environmental groups, including NRDC, remains highly controversial. Many scientists and environmentalists believe the move stripped the grizzly of federal protection just as one of its key food sources was disappearing.
The U.S. Fish and Wildlife Service went ahead with the delisting based on the belief that the beetle outbreak wasn't a problem, and that if it became one, the bears would adapt. As omnivores, grizzlies do eat more than pine nuts. But researchers have found that three times as many grizzlies die in bad whitebark pine years as in good ones. Abundant pine nuts keep the bears busy eating at remote, high altitudes, Willcox says, "and that keeps them from seeking food at lower elevations, where they're more likely to run into conflicts with people and livestock - and get killed."
In its delisting ruling, the Fish and Wildlife Service found that only 16 percent of whitebark pine forests in the Greater Yellowstone Ecosystem had been killed by beetles as of 2005. Logan, who has been studying the beetle for more than 20 years, believes that figure is dead wrong. The citizen scientist data could prove it. "We're on pace to lose 80 percent of our whitebark pine forests within the next five to ten years," Logan says. "There are a few exceptions, like the Central Wind River Range in Wyoming, where it stays cold enough in winter, but the whitebark pine is going to be functionally lost in the Greater Yellowstone."
One key to stemming the decline may be to find trees that show some resistance to the beetle. The pine needles that Logan saw on Emigrant Peak were green, not red like those on beetle-killed trees. But then he peeled back a patch of bark and saw the tiny tunnels - "galleries" - made by the beetles. The tree had been so recently killed that its needles hadn't yet turned red. He checked out another. Dead. He kept going. Dead. Dead. Then he saw something different. In one of the whitebark pines, the galleries stopped short, indicating that the beetles had halted after making their initial attack. "Whoa!" he thought to himself. "Living tree."
It was a rare survivor. Whitebark pines respond to the beetles by trying to flood them out with sap. It almost never works. But this tree had released some sort of secondary resin that killed the beetles. "It was very exciting," Logan recalls. "It meant that the capacity to resist the beetles exists in the gene pool, if only in a few trees." He marked the tree and added it to the database.
It's not a silver bullet, but it's a start. If scientists can figure out what allowed this particular tree to fend off the attack, they may be able to replicate the ability in future generations, possibly by replanting ravaged forests with beetle-resistant whitebark pines. It's a long shot, and it requires funding for research into what made Logan's tree different. But it might give the forests, and the grizzlies, a fighting chance.
Bruce Barcott, author of The Last Flight of the Scarlet Macaw (Random House), writes often about the environment.