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News from the Keweenaw Peninsula Posted April 7, 2003 Text © 2003 Michigan Tech University Press Release. Photos © Rolf Peterson. Reprinted with permission.

Research shows snowmobiles stressful to wolves, elk

HOUGHTON -- The straight poop on snowmobiling is that it's stressful to wolves and elk.

Such are the implications of fecal analyses undertaken by Professor Rolf Peterson, of Michigan Tech's School of Forest Resources and Environmental Science, and other researchers in Yellowstone, Isle Royale National Park and Voyageurs National Park, in Minnesota. However, Peterson suspects, snowmobiles are the least of a typical wolf's worries.

MTU Professor Rolf Peterson photographed these wolves crossing the ice along the shore of Isle Royale. (Photo © and courtesy Rolf Peterson. Reprinted with permission.)

Scientists compared the hormone levels of wolves in Isle Royale, where there are no snowmobiles, to those of wolves in Voyageurs, where there is snowmobiling aplenty. Consistently, the Voyageurs wolves exhibited higher levels of stress hormones.

In addition, the scientists noted another direct relationship between snowmobiles and stress. When snowmobile use tumbled 37 percent in Voyageurs between the winters of 1999 and 2000, fecal stress hormone levels also dropped in the park's wolf population--by 37 percent.

An Isle Royale wolf family poses for a photo by MTU  Professor Rolf Peterson, who has done wildlife research on the island for several years. The female in the foreground stands close to her pup on the ice, while the male walks behind them. (Photo © and courtesy Rolf Peterson. Reprinted with permission.)

Researchers also found that stress hormones in elk living in Yellowstone National Park fluctuated weekly, rising and falling in direct correlation with snowmobile activity.

"Those are pretty compelling data, but they're hard to interpret," Peterson said. "Does snowmobiling matter to elk or wolf populations, or to individuals, for that matter? Probably not." The availability of food is a far more compelling issue to wolves, he said. "And for elk, probably what counts is surviving the winter, when they are most vulnerable to wolves."

Such studies are made possible by a relatively new research technique. Fecal analysis is providing extensive information about animal populations without traumatizing the individuals.

"We're using animal droppings in a wide variety of ways we never dreamed of," Peterson said. "We're just completing a two-year study of wolf droppings, and it looks like we'll be able to characterize each wolf using fecal DNA. We can track an individual for its entire life, and it's completely non-invasive." 

Researchers can also test the cows' fecal pellets to determine if they are pregnant.

Scientists are already using a related technique, urinalysis, to indicate a moose's physical condition. "If an animal isn't getting enough to eat, it burns muscle, which shows up as urea in its urine," Peterson said.

Without asking the animals directly, it's probably fair to say they'd prefer this kind of information gathering to the traditional alternative: being shot with a tranquilizer gun and poked with a needle to draw blood.

Peterson's research linking stress hormones in moose and elk with snowmobile activity was published in the journal Conservation Biology in 2001. The coauthors are Scott Creel and Robert Garrott, faculty members at Montana State University; graduate students A. Hardy and Jennifer Sands of Michigan State University; and Jennifer Fox, a graduate student at Michigan Tech.

Editor's Notes: Mike Phillips of the Turner Endangered Species Fund will give a talk: "Wolves, Condors, and Trout: A Private Effort to Save Nature" at 7 p.m. on Monday, Apr. 7, in G002 Hesterberg Hall, the Forestry Building on the MTU campus. A steadily growing gray wolf population in the western Great Lakes states and a highly successful reintroduction program in the northern Rocky Mountains have prompted the U.S. Fish and Wildlife Service to change the status of gray wolves in these areas from "endangered" to the less serious "threatened" designation under the Endangered Species Act. See the U.S. Fish and Wildlife Web site on Gray Wolf Recovery. In anticipation of the Rocky Mountain gray wolf's full recovery and removal from the federal endangered species list, Montana wildlife officials recently released a draft environmental impact statement for Montana's wolf Conservation and Management Plan, presenting five wolf management alternatives for public comment. Read details on the Montana Fish, Wildlife and Parks Web site. According to Defenders of Wildlife and the Sierra Club, conservationists have expressed strong disappointment that the U.S. Fish and Wildlife Service recently rescinded proposed gray wolf recovery efforts for the Northeast. See details on the Enviro-Mich Web site.

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