For years, biologist Robert Crabtree heard stories of fur trappers who claimed to have seen the elusive "gray ghost of the Beartooth Plateau."
Like many of his scientific colleagues, Crabtree gave little credence to the folksy reports until one bone-chilling morning in January 1991. Flying over Montana's Beartooth mountains, he saw a four-legged creature below, ambling across snowdrifts 200 inches deep, camouflaged in a coat of mottled, smoke-colored fur. At that moment, Crabtree, who heads the Yellowstone Ecosystem Studies research organization in Bozeman, Mont., became more than just a believer in the existence of an anomalous mammalian predator high in the northern Rockies.
Due in large measure to his tenacious quest to unravel a century-old mystery, researchers now may be on the trail of a unique breed of wild dog left over from the Ice Age.
In a peer-reviewed manuscript being prepared for publication to a scientific journal, Brad Swanson, a Purdue University doctoral candidate, presents what some are calling "tantalizing" evidence of a relic fox that survives where its lowland cousins cannot. "I honestly didn't believe we would find what we found," says Mr. Swanson, who this summer completed three years' worth of DNA laboratory analysis at Purdue and at the University of California in Los Angeles. "After my jaw dropped, I've been walking around with a grin on my face," he added. "The results, while not conclusive, are thrilling."
What Crabtree witnessed - and what Swanson's genetic testing suggests - is the existence of a semi-isolated, New World "tundra" fox that differs significantly in its behavior and physiology from the common red fox of the Old World brought to this continent by European noblemen centuries ago. Equally revealing is the fact that this bushy-tailed canine and others of its clan prefer to inhabit stark, treeless terrain 2 miles above sea level in abominable conditions.
While the discovery certainly doesn't rate on the cosmic scale of say, proving the existence of life on Mars, or even on the level of cataloging a new species of primate in the jungles of Amazonia, researchers say the discovery is significant because the rare fox, for perhaps the last 20,000 years, resided - undetected - next to one of the most studied wildland preserves on earth, Yellowstone National Park.
"If it weren't for the trappers who noticed the novel gray color of these foxes, nobody in a million years would have even suspected that we might have a distinct population of red fox that has been there since the end of the Pleistocene," Swanson says. "We often have a very simplistic view of the world based upon what we see, but it's revelations like this that broaden how we interpret what's around us."
One theory being kicked around by evolutionary ecologists, who have witnessed a similar phenomenon in the northern Cascades of Washington and the Sierra range in California, is this: At the end of the epochal Wisconsin glacial period 10,000 to 20,000 years ago, it is possible that as giant sheets of ice receded northward into Canada, certain populations of animals, like the Beartooth fox, were left stranded.
Instead of migrating along with the glaciers back to the Arctic tundra, the foxes simply climbed higher in elevation on the Beartooths until they reached terrain that closely mimics the kind of native habitat usually found a couple of thousand miles north.
In fact, the windswept expanse of the Beartooth Plateau holds the largest continuous sprawl of alpine "tundra" in the lower 48 states. Besides the foxes, field biologists have identified isolated populations of endemic plants and insects.
Since most of the remote Beartooth mountains are managed as federal lands by the US Forest Service, Crabtree initially went to that agency with a request for funding to conduct a survey. He was met, however, with a rejection from Forest Service officials, who said they had neither the money nor the inclination to pursue the matter.
That's when Swanson and Yellowstone Ecosystem Studies researchers stepped forward and collected tissue specimens from not only live animals, but also skins taken by trappers. While some skeptics see the fox as yet another rare animal that might be used to stop development on private and public lands, Crabtree and Swanson say they have no political agenda.
Some of the physical characteristics that distinguish the Beartooth foxes from their red fox cousins are (1) a mottled gray color phase found nowhere else in North America; (2) a body frame that, compared to other red foxes, is smaller but stouter; and (3) a behavioral preference for choosing habitat that other foxes avoid. Most revealing, however, are the differences in DNA structure.
Swanson ascertained that there were two semi-isolated subpopulations of red fox each delineated from the other by variations in altitude and corresponding habitat. While there appears to be frequent mixing of the lowland and middle-elevation populations, the animals found from 8,000 to 9,000 feet to the tops of mountains were isolated from their brethren.
Swanson compared tissue samples taken from lowland fox populations, foxes found at medium elevations, and then samples from specimens found in the Beartooths. He ensured that no bias was injected into his results by having the samples tested blindly.
"When we did the DNA work, we didn't know which animals were from high or low elevations. The testing was run blind and scored blind so that I couldn't subconsciously or consciously manipulate the outcome."
The DNA analysis, though admittedly based upon a limited amount of tissue samples, begs far more questions than it answers. Among them: What has enabled the fox to survive in such a hostile environment? What are the ramifications for this Beartooth island population if global warming models prove to be accurate and alpine habitat is altered by higher temperatures in the 21st century?
In the months ahead, Crabtree and Swanson hope to gain funding for a survey that will compare the genetics of the Beartooth foxes against others elsewhere in the mountainous West, in lowlands, and on the tundra of Alaska. "The Beartooths are like a living museum of the the last glacial age," Crabtree says. "Unfortunately, they have never received the kind of critical scientific examination given to Yellowstone beginning in the late 1860s and continuing to this day.
"Where the fox is concerned, it boils down to the premise that you can't protect what you don't understand," Crabtree says. "Although the trappers knew it was special, it has taken us longer to figure it out."