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Wolves Decline, Moose Increase
The lack of winter weather explains many of the changes in the annual wolf-moose survey at Isle Royale National Park, according to Rolf Peterson, professor of wildlife ecology. The 2002 survey counted 17 wolves, compared to 19 last year. The moose population increased from about 900 last year to 1,100 in 2002. The Isle Royale wolf-moose survey is the longest running predator-prey study in the world, now in its 44th year. Peterson has conducted the study for 32 years. "The significant factor was a lack of winter," Peterson said, referring to the very light snowfall this year. "Moose were in places where we don't normally see them in the winter--on hillsides and out of the conifer swamps." As an island in the middle of Lake Superior, Isle Royale presents a unique opportunity for such research. Peterson said the wolves suffered a mortality rate of almost 50 percent this winter and that last yearŐs seven pups kept the population near steady. "We watched about 15 encounters between wolves and moose this winter," he said. "The moose were almost always intimidating, so the wolves didnŐt bother to attack." Typically the wolves prey on old moose and young calves. But with little snow cover, the moose could move more freely and avoid the wolves. Ę The wolf-moose study is supported by Isle Royale National Park, the National Science Foundation, the Earthwatch Institute, and a number of individual donors. For more information see the web. |
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