The southern lynx and hare populations, though small, don’t fluctuate as much as those in the north. Because the forests are naturally patchier, the timber harvest is heavier and other predators are more common, hares tend to die off before reaching boom levels. In Montana, the cats are always just eking out a living, with much lower fertility rates. They prowl for hares across huge home ranges of 60 square miles or more (roughly double the typical range size in Canada when the living is easy) and occasionally wander far beyond their own territories, possibly in search of food or mates. Squires kept tabs on one magnificent male that traveled more than 450 miles in the summer of 2001, from the Wyoming Range, south of Jackson, over to West Yellowstone, Montana, and then back again. “Try to appreciate all the challenges that animal confronted in that huge walkabout. Highways, rivers, huge areas,” Squires says. The male starved to death that winter.
Of the animals that died while Squires was tracking them, about a third perished from human-related causes, such as poaching or vehicle collisions; another third were killed by other animals (mostly mountain lions); and the rest starved.
The lynx’s future depends in part on the climate. A recent analysis of 100 years of data showed that Montana now has fewer frigid days and three times as many scorching ones, and the cold weather ends weeks earlier, while the hot weather begins sooner. The trend is likely the result of human-induced climate change, and the mountains are expected to continue heating up as more greenhouse gases accumulate in the atmosphere. This climate shift could devastate lynx and their favorite prey. To blend in with the ground cover, the hare’s coat changes from brown in summer to snowy white in early winter, a camouflage switch that (in Montana) typically happens in October, as daylight grows dramatically shorter. But hares are now sometimes white against a snowless brown background, possibly making them targets for other predators and leaving fewer for lynx, one of the most specialized carnivores. “Specialization has led to success for them,” says L. Scott Mills, a University of Montana wildlife biologist who studies hares. “But might that specialization become a trap as conditions change?”
The lynx’s precarious status makes even slight climate changes worrisome. “It’s surprising to me how consistently low their productivity is over time and how they persist,” Squires says. “They’re living right on the edge.”
To follow the cats into the folds of the Rockies, Squires employs a research team of former trappers and the hardiest grad students—men and women who don’t mind camping in snow, harvesting roadkill for bait, hauling supply sleds on cross-country skis and snowshoeing through valleys where the voices of wolves reverberate.
In the early days of the study, the scientists retrieved the data-packed GPS collars by treeing lynx with hounds; after a chase across hills and ravines, a luckless technician would don climbing spurs and safety ropes, scale a neighboring tree and shoot a sedation dart at the lynx, a firefighter’s net spread below in case the cat tumbled out. (There was no net for the researcher.) Now that the collars are programmed to fall off automatically every August, the most “aerobic” (Squires’ euphemism for backbreaking) aspect of the research is hunting for kittens in the spring. Thrillingly pretty, with eyes blue as the big Montana sky, the kittens are practically impossible to locate in the deep woods, even with the aid of tracking devices attached to their mothers. But the litters must be found, because they indicate the population’s overall health.
Squires’ research has shown time and again how particular lynx are. “Cats are picky and this cat’s pickier than most,” Squires said. They tend to stick to older stands of forest in the winter and venture to younger areas in the summer. In Montana, they almost exclusively colonize portions of woods dominated by Engelmann spruce, with its peeling, fish-scale bark, and sub-alpine fir. They avoid forest that has recently been logged or burned.
Such data are instrumental for forest managers, highway planners and everyone else obligated by the Endangered Species Act to protect lynx habitat. The findings have also helped inform the Nature Conservancy’s recent efforts to buy 310,000 acres of Montana mountains, including one of Squires’ longtime study areas, from a timber company, one of the biggest conservation deals in the country’s history. “I knew there were lynx but didn’t appreciate until I started working with John [Squires] the particular importance of these parcels of land for lynx,” says Maria Mantas, the Conservancy’s western Montana director of science.
Squires’ goal is to map the lynx’s entire range in the state, combining GPS data from collared cats in the remotest areas with aerial photography and satellite images to identify prime habitat. Using computer models of how climate change is progressing, Squires will predict how the lynx’s forest will change and identify the best management strategies to protect it.
The day after our run-in with M-120, the technicians and I drove west three hours across the shortgrass prairie, parallel to the front of the Rockies, to set traps in a rugged unstudied zone along the Teton River, in Lewis and Clark National Forest. The foothills were zigzagged with the trails of bighorn sheep, the high peaks plumed with blowing snow. Gray rock faces grimaced down at us. The vastness of the area and the cunning of our quarry made the task at hand seem suddenly impossible.