The Long View
Isle Royale National Park draws visitors who like nature rugged and remote. It's also the site of the longest-running study ever of a predator and its primary prey--even as global warming shows signs of upsetting the natural balance.
A supremely fit Scandinavian from Minnesota with sparkling blue eyes and a gray-streaked blond beard, Peterson was nine years old when the study began, and like most lads of that age, he was clueless about the natural world. But a National Geographic article by Mech and Allen piqued his curiosity about Isle Royale. He hiked its trails twice while a college student. And as Rolf tells the story over a lake trout dinner at the lodge, he wrote to Purdue in his senior year and inquired about doing graduate work there. "The thick packet they sent back didn't mention Allen or wolves, so I figured the study was over. Then I saw a TV documentary called Wolfmen and realized I had written to the wrong department." This time Allen got the letter and offered Rolf the next time slot for graduate work on the island.
Not surprisingly, there's a minuscule cast of mammals on this isolated island, including just one species of mouse, and only five amphibians. How they arrived is anyone's guess, but as Rolf points out, "They had 10,000 years to do it after the glaciers retreated." Woodland caribou, Canada lynx, and marten were once present but disappeared in the early 1900s. Moose, however, seem to be relative newcomers, judging by the absence of bones at ancient Indian campsites. These large ruminants are strong swimmers, and biologists believe the ancestors of today's population paddled over from Canada, a distance of 20 miles, about 1900. They found a moose paradise: a virgin forest with no predators. But within three decades their numbers had swelled to several thousand, the forest had been browsed to nubs, and a disaster loomed. By 1935 only 200 starving moose were left on Isle Royale. Then a forest fire created a brand-new forest and the herd slowly regained its health if not its former numbers. However, reports of new moose starvation in the unusually hard winter of 1949 prompted a clamor for control measures, either through hunting or by introducing wolves.
Nature, however, had already intervened. That winter a mated pair of wolves crossed over an ice bridge linking the island to Ontario. "It was an extraordinary event," Dave Mech told me years later. "The water would have to be cold and calm enough for the lake to freeze over. Then you need wolves predisposed to make the long trek. Chances of that happening are pretty remote or Isle Royale would have had wolf packs before the 1940s." In short time a balance between predator, prey, and vegetation was established on Isle Royale. It lasted until the summer of 1981, when a strict rule barring pets from the park was ignored.
The Petersons' research base sits across the long, narrow harbor from Daisy Farm, Isle Royale's largest campground and the first night's stop for most backpackers. They live in a simple cabin built of logs laid atop beach rocks by Jack Bangsund, one of the island's last commercial fishermen. Rolf flies the Norwegian flag over the camp in Bangsund's honor. He's also erected a yurt ("a Mongolian nomad's home") back in the trees, where he can work secluded from the hundreds of visitors who are dropped off by a tour boat and stare in awe at a yard full of moose bones, skulls, and antlers. But the Bangsund site has been more than a workplace since the Petersons arrived. As Candy writes in a book in progress, it also served as a summer nursery, home base, and launching pad for their two sons.
The couple's mission from May to October involves a lot of footwork, including trapping and radio-collaring a wolf from each pack (there are three at present); tracking their movements with antennas from high points on the ridges; and locating wolf dens and counting pups. (Three summers passed before the Petersons found their first den, in an old dry beaver lodge.) Then there's scouring the island for the bones of both moose and their tormentors, a task now largely assigned to Earthwatch Institute volunteers. The bones reveal a great deal more than stories about the owner's life and death. For example, that an aged moose had severe arthritis or a broken jaw due to infection when wolves brought it down. Scientists, Rolf explains, have discovered that both animals are "biological time capsules." Plants incorporate carbon dioxide from the air into leaves and twigs that are eaten by moose that will probably be eaten by wolves. They also accumulate traces of other environmental pollutants. Thus the animals' teeth store a record of large-scale ecological change, from radioactive fallout during the period of Cold War nuclear tests to a sharp decline in levels of lead and mercury and--most notably--the inexorable rise of atmospheric carbon dioxide levels from our relentless burning of fossil fuels. Unknowingly, moose and wolves have mapped the road to global warming that now threatens their survival on the island.