In 2014, a 20-year-old grizzly bear named Ethyl made an epic 2,800 mile walkabout through Montana and Idaho. U.S. Fish and Wildlife Service biologists knew of her movements because of the GPS collar she wore, which sent weekly data to a satellite. Federal Grizzly Bear Recovery Coordinator Chris Servheen called her traverse into Idaho via the Bob Marshall Wilderness and Mission Mountains, which involved navigating through main streets, landfills, backyards and crossing Interstate 90, “bizarre.” While male grizzlies make big movements, females rarely venture far. Yet this was but one of several similar carnivore peregrinations documented in the last fifteen years via GPS-collar technology.
Other carnivores have followed. In February 2008 while doing a marten study near Lake Tahoe, Oregon State University graduate student Katie Moriarty photographed a wolverine with her trail camera. California’s first substantiated wolverine sighting since the 1920s, the grainy image created a furor. Genetically related to Rocky Mountain wolverines, the animal had dispersed at least 900 miles. Then there was the young male cougar who in 2011 made a 1,500 meander from the South Dakota Black Hills to suburban Connecticut, looking for new prospects, only to become roadkill. Or the female wolf who in late 2014 wandered from the Greater Yellowstone Ecosystem to the Grand Canyon, wearing an inactive radio collar. DNA tests revealed that she was a pure wild wolf.
Audacious as such dispersals may seem, these peripatetic carnivores can’t help making them. This behavior is imprinted in their DNA, in the shape of their bodies, and in how their minds work. Moreover, they do it with casual grace, as if such heroic dispersals amounted to just another day in their lives. There goes a wolf, loping a thousand miles in a harmonic, energy-conserving gait, its hind feet falling perfectly into the tracks left by its front feet. And a wolverine, effortlessly running up mountains and back down in minutes, covering more ground and elevation more rapidly than any other terrestrial mammal. If such behavior were a simple act of will, most of these stories would have happy endings. But nevertheless, these dispersals fill me with hope that perhaps we’ll soon get it right, given the opportunities and powerful lessons these animals are providing.
In the North American West, the primary corridor carnivores have been using for dispersal since the end of the last ice age extends from Alaska to Mexico. Twelve thousand years ago, two ice sheets covered much of this continent. As they melted, a path opened between them, enabling passage of creatures such as grizzly bears. Today, animals continue to use this ancient corridor. Indeed, I like to think of it as a “carnivore way,” because of the carnivores who have worn deep trails in this pathway over millennia.
Obstacles to this basic need to roam, such as human development, can provide formidable threats to long-term survival of many species. For the large carnivores, it’s not just about losing the freedom to move, it’s about losing a natural process. They and other species use dispersal as a key survival mechanism, to maintain genetic diversity and adapt to climate change.
To learn more about the challenges grizzly bears, wolves, wolverines, lynx, jaguars, and cougars face, in 2013 I traveled the Carnivore Way. I talked to dozens of ecologists, ranchers, and conservationists, and immersed myself in the landscapes these animals inhabit. These travels formed the basis for my recent Island Press book, The Carnivore Way: Coexisting with and Conserving North America’s Predators. In future posts, I’ll share some of these species’ stories and the astonishing lessons I learned along the way.