Science: Nature's Housekeeper

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"Wolves have been pushed around,'' says Biologist C. Gordon Fredine of the National Park Service. "People resent them."

Wolves resent people, too, occasionally eating them down to their boots. Result: U.S. wolves have been all but exterminated by resentful U.S. people. But Biologist Fredine reports that a study being conducted on Lake Superior's Isle Royale by the Park Service and Purdue University shows that wolves serve a useful purpose in the balance of nature.

Isle Royale, a national park, is 45 miles long and 20 miles from the Ontario shore. Originally it was covered with forest. Moose arrived about 1900, probably crossing from the mainland on the ice. With no hunters and no predators, the moose multiplied unchecked, and by 1930 had nibbled the forests bare of browse. Then came a great die-off; the big herds of feeble, emaciated moose declined until there were only 200 survivors. When the browse grew back, the moose herds grew with it—but then another die-off came around 1950.

To stop this tragic cycle, park authorities tried importing four zoo-bred wolves. But they preferred living on human handouts, and had to be sent back to the zoo. Eventually, wild wolves from Canada crossed on the ice. Purdue and Park Service biologists, some of whom have braved the island's fierce and lonely winter to study the working of nature's balance, report that the wolves' system is to cut a single moose out of a herd and keep nipping at him day after day until he weakens. Sometimes it takes a week. In crusted snow that supports wolves, the most formidable moose cannot escape. But deep, soft snow is a refuge for moose; wolves flounder in it helplessly, and there the moose can turn on its tormentors and stamp out their lives. Since the wolves came, reports Dr. Fredine, the island's population has stabilized at about 300 moose and 25 wolves.