Since Errington, the language of predation has grown more complex. Predator and ungulate biologists speak of limitation, regulation, and control. There has been much disagreement about what each of these terms means. “Control,” for example, is defined by one authority as the maintenance of a population at some level, and controlling influences could be things like lack of water or breeding sites. Another author says control means a planned attempt by humans to manipulate population size through hunting or culling. Without agreement on their definitions, biologists have at times used all three terms interchangeably. There seems to be increasing agreement and more careful use of the terms “limit” and “regulate.” Predation is a limiting factor if it causes a prey population to decline or causes a decline in the birth rate. Limiting can be either additive or compensatory. Predation is a regulating factor if it stabilizes the number of prey in a specific area over time, and if predators take proportionately more of the prey species when they are abundant than when they are uncommon. Regulating is thus a subcategory of limiting.
The essential question posed by the terms, however, is this: Can wolves by themselves cause a prey population to decline and remain at lower levels? Before the middle of the century, only Murie and Cowan had sought to answer this question. And by then, wolf habitat was too remote, and wolves themselves were too elusive, to make prolonged study seem worth the effort. To understand a predator-prey system, one would have to spend years watching wolves in a remote place with expensive logistical support. Such a study would require years of data on the age structure of the prey population and the overall number of predators and prey. It would call for evidence of the frequency with which wolves ate each prey, and thus continuous study of the contents of wolf stomachs or scats. Funding such a study, when predation was still regarded largely as a moral and economic problem, seemed very unlikely.
But in the 1950s, an accessible and contained wolf population became available for study on Isle Royale, an island national park near the north shore of Lake Superior. Until the late 1940s, wolves had been absent from the 210-square-mile island. Moose had swum to the island sometime before 1912, and, without wolves, they had grown so numerous that there were efforts to transplant them to the Michigan mainland.
Adolph Murie had studied the eruption of the moose population on Isle Royale in 1930 and had suggested introducing wolves as a way to keep the moose from overrunning the island. A similar proposal was made in 1951 by Michigan biologist A. M. Stebler, but the park superintendent opposed it because wolves were “vicious beasts” and he feared reintroduction would be bad public relations. Durward Allen says today that he had been dreaming of wolves on Isle Royale for years: “I was an undergraduate when I saw the possibility of moving some of the wolves from Michigan to that island.” He confesses that when he was a student he and a close friend, Lee Smits, talked about sneaking wolves onto the island.
Smits, a Detroit conservationist, eventually did put wolves on the island. In 1952, Smits persuaded the Park Service to agree to an introduction. Four wolves born in the Detroit Zoo were brought to the island. At first they were kept in pens to acclimatize; then the pens were thrown open, in the hope that the wolves would eventually move out on their own into the wild. But the wolves were too habituated to humans, and too little skilled at moose hunting. They hung around campgrounds and cabins, scaring tourists and tearing up the nets and laundry lines of fishermen. The Park Service trapped one of them and removed it to the mainland, and shot two of the others. The fourth, Big Jim, a wolf reared at home by Smits, vanished into the wild.
Other events overtook Smits’ dream. In 1948, while Farley Mowat was drafting his book, a pair of wild wolves crossed the ice bridge to Isle Royale from the Canadian mainland in winter. Unlike Smits’ captive-reared wolves, they knew how to hunt, and, as wild wolves do, they remained quietly out of view. Humans occupied the island only during the summer months, when wolves generally remain out of sight in the dense underbrush, and not in the winter, when tracks are easily seen. Just months before the tame wolves were put out, a park ranger saw wolf tracks, and shortly after the release a visitor reported seeing wild wolves. Little was made of these sightings because the Park Service was committed to the introduction effort. But then, in 1953, after the release and removal of captive wolves had perhaps made park officials more attentive to wolf sightings, James Cole, the park biologist, saw a pack of four wolves.
When Durward Allen, then working for the U.S. Fish and Wildlife Service in Washington, D.C., heard that wild wolves had arrived on the island, he left his job and took a position teaching at Purdue University, anticipating that the position would allow him to study the wolves on Isle Royale. He felt a sense of mission about the prospect. “There were some things that were rife among most human beings, like the Little Red Riding Hood story,” he says today. “The old-timers who lived in the woods claimed to know everything, but they knew nothing. The old-timers had taken over the sporting magazines, and the stories they told were a lot of hogwash. But people believed them. In North America, nobody was getting eaten up by wolves. Nobody took any trouble to expose wolf dynamics or what they were doing to their prey population. It was clear that the people who wanted to understand wolves were on their mettle: they had to prove everything. Before my Isle Royale days, I had concluded that the scientist is going to have to get into this and outdo the old-timers.”
It was for Allen a chance to change fundamentally the way people looked at nature. “People don’t think ecologically,” says Allen. “This is one of our problems. They don’t have an ecological background on which to hang an animal. And most of them are dominated by their religious culture,” which in some places still associates wolves with evil. Allen saw in Isle Royale a chance to educate people about the importance of ecological thinking. It would take him four years to get organized—to find funding and people who could do the work.
While he taught classes at Purdue, Allen would require a graduate student to man the island research. He chose David Mech, then a recent graduate of Cornell University, to conduct the fieldwork. Mech had grown up in Syracuse, New York, in a family that camped every summer in the Adirondacks. Without knowing it, he was already engaged in a conversation with Durward Allen. Allen had written the Boy Scout wildlife merit-badge handbook which Mech had read as a boy, and through it, perhaps, Allen had summoned him years before they ever met. Mech learned trapping as a boy at a New York State Department of Conservation summer camp in the Catskills from counselors who were wildlife-management students from Cornell. The experience gave focus to his life. “It headed me in the right direction,” he recalls today. “It headed me to Cornell for a wildlife major.”
As an undergraduate at Cornell, Mech worked on a study of black bears. His chore was to ear-tag the bears. It was primitive work. Bears were trapped in leghold traps; to put an ear tag on one, a gang of students had to spread-eagle the bear and hold it down while someone injected a drug which could only be administered through the abdominal wall. One person held the bear in a choker, someone else noosed a hind leg, and a third noosed another leg, until five or six of them spread the bear out and turned it over. That, and Mech’s experience alone in the Adirondacks in winter trapping fisher, persuaded Allen that Mech was the right person to wrestle with wolves in the wilds of Michigan. That Mech had written popular-magazine stories about some of his trapping exploits made him more desirable. Allen saw a need to educate the public in this new view of predators, and Mech’s communication skills, he felt, would be important assets.
Allen also felt he needed a student who did not jump to conclusions. At their first meeting, Allen saw a quiet caution in the younger man. Mech recalls that first meeting: “Here I was a senior in college, twenty years old, and Durward wanted to talk to me. The only other state I’d been in was Pennsylvania, and Durward was talking to me about this island somewhere out in the West, this huge island with wolves and moose. It seemed almost mystical. I hadn’t a clue why he was telling
me this. And I told him it sounded like a great project. I said, ‘I wish you luck in it.’ And he said, ‘Well, I’d like you to do the study.’
“I just couldn’t believe it. I never thought I’d get, in my life, to some place where I’d see a wolf track. Suddenly, my horizons were greatly expanded. I would see wolf tracks in my lifetime, and I might even see wolves.”
He would indeed. Since then, Mech has studied wolves in Michigan, Minnesota, Montana, and Alaska, in Russia, India, and Italy, and on remote Ellesmere Island in the Canadian Arctic. He succeeded Douglas Pimlott as chairman of the International Union for the Conservation of Nature’s wolf-specialist group and served on the recovery team for the eastern timber wolf. When the media discover wolf controversy, reporters call him. Today, Mech is considered the dean of wolf biologists. He has been called “Mr. Wolf”—both in praise and in sarcasm, for wolf biology is contentious work. Hawk-nosed and thin-lipped, he has a closely trimmed beard that is beginning to show hints of gray. His brown eyes are deep-set, and the folds over the corners tell of long hours spent looking at things. He is deliberate and watchful, with a wolflike curiosity—though he would bristle at the wolf comparison, because he would be the first to say that one should never attribute human qualities to wolves.
Mech began his work on Isle Royale in 1958. In February and March, he flew over the island, tracking and watching the wolves from the air. He found it possible to follow them thus in the snow, and even to circle and watch as they attacked and killed moose. The wolves had markedly increased in number since 1953. One February afternoon, he would later recall in The Wolves of Isle Royale, he was flying after a pack of sixteen wolves along the lakeshore when they stopped and pointed their noses toward an old cow moose two hundred yards away. They went inland and came out of the tree cover twenty-five yards from the moose, which fled. They chased her and caught up. One wolf grabbed a hind leg, but the moose shook it off and trotted through a clump of spruce. They caught up again, and several wolves grabbed her flanks, but she shook them off and continued. Then a wolf darted in, grabbed her by the nose, and hung on. As she stood trying to shake him off, several other wolves fastened their jaws on her flanks and rump. The wolf on her nose held its grip for at least a minute, while the cow dragged it and several other wolves a hundred yards. She shook them all off and ran into the woods, kicking and trampling wolves, to stand next to a balsam fir, so that the wolves could only attack from one side. The wolves simply lay down in the snow and waited. Every time a wolf walked close to the moose, she would threaten. But she was weakening and stiffening from her wounds. Mech had to break off the observation before nightfall. When he returned the next morning, the wolves were feeding on the moose’s carcass.
If he found a kill, Mech would land and pick up bones or teeth and determine its age and condition. He discovered he could walk right up to the kill and the wolves would flee into the forest. They were never threatening. In summers, he walked the trails of Isle Royale, looking for wolf tracks and scats, and listening for howls to locate wolf dens, but he rarely saw wolves. In the fall, he counted the moose and estimated the ratio of cows to calves.
Mech found that the wolves on Isle Royale acted just as Murie said they acted at Mount McKinley: they took the young, the old, and the sick. Healthy adult moose could either escape or turn and fight, and those that fought invariably survived. Despite the arrival of wolves on Isle Royale, the moose population did not decline.
Isle Royale excited newspapers and television reporters. Mech and Allen published an account of Isle Royale’s wolves in National Geographic magazine in 1963, and Mech wrote a number of popular articles in succeeding years. Mech’s photos were widely published and they gave the impression that Isle Royale was a place where people could effortlessly watch wolves hunt. “It grabbed the public’s imagination,” says Mech. “Newspapers were always hounding me for interviews. The public didn’t know about Olson’s or Murie’s or Stenlund’s studies. But once it got around that this island was a closed system where predation could be studied intensively, there was a lot of interest. The study focused a great deal of public attention on wolves.”
Through the articles and interviews, Mech explained that most of what was written about wolves was myth. His book The Wolf replaced Young and Goldman’s as the standard reference on wolves for biologists and the public alike. And Allen followed a few years later with The Wolves of Minong (the Ojibwa name for Isle Royale), detailing the Isle Royale study and its findings. “We showed that a lot of the crap that came out in the sporting magazines wasn’t true,” says Allen. “Wolves don’t characteristically eat people—they’ll run away rather than attack a human being. We proved the wolf is a very intelligent animal that can accept human beings.”
Most important, Isle Royale seemed to show that wolves did not regulate the prey. Mech had found there that moose from two to seven years of age were almost invulnerable to wolves, and that calves and elderly moose constituted nearly all the winter kills. The calves were smaller and weaker. The older moose tended to have infestations of moose tick and hydatid cysts in their lungs. Sometimes the cysts were so large and numerous that the moose probably couldn’t breathe freely. In his Ph.D. thesis, published as The Wolves of Isle Royale by the National Park Service in 1966, Mech observed that high twinning rates among moose were generally regarded as signs of a healthy moose herd, and the Isle Royale moose herd had one of the highest twinning rates in the literature. He tentatively attributed this high rate to wolf predation, which kept the moose population within the limits of the food supply and culled out the unhealthy individuals. “The Isle Royale moose population,” he concluded, “probably is one of the best ‘managed’ big game herds in North America.”
Mech also challenged the idea that wolves were unfailing killers. He has probably seen more wolf kills than any other living human. “I’ve watched wolves kill everything from deer to caribou to moose to musk oxen to Arctic hare,” he says, “and, by golly, they get a small percentage of the prey, pure and simple.” On Isle Royale, Mech saw wolves test seventy-seven moose in hunts and succeed in killing only six of them. He believes wolves approach about twelve deer or moose for every one they actually catch.
Mech believes that this is one of his most important discoveries, because it forces us to think differently about the wolf. “The prey are always ahead of the predators,” he says. “If predators were ahead of the prey in an evolutionary sense, they wouldn’t hunt twelve times for every kill, and they wouldn’t tend to kill fawns and old individuals, but would instead kill a cross-section of the prey population. The typical prime member of the prey population is invulnerable to the wolf. The wolf is essentially a glorious scavenger. They just don’t wait for the prey to die.”
Other researchers also found that wolves failed more often than they succeeded in killing prey. Ludwig Carbyn and S. M. Osenbrug studied the relationship between wolves and bison in Wood Buffalo National Park in northern Alberta from 1978 to 1981. Bison provide 80 percent of the wolf’s diet there in summer, and more in winter. The two researchers watched 143 bison-wolf interactions, ranging from “close watching of bison” by wolves, to kills. If the wolves saw some sign that a bison was weak, they tested the herd with a run at them. Half of the time, bison stood their ground when wolves first charged, and the wolves gave up and moved on. Whenever the bison fled, the wolves attacked. If a fleeing bison got angry and turned to charge the wolves, the wolves would run right by that bison, continuing to pursue the rest of the herd, and Carbyn would be treated to the sight of the one brave bison passing the wolves to catch up with his own herd. Wolves would stay with a herd of bison for as long as six days, pressing the prey, waiting for something to happen. In all those encounters, there were seventeen attacks and only three kills.
Clearly, even if they are attacked, prey often escape. “We frequently observed bison with missing tails and suspected that wolves were responsible,” wrote Carbyn. William Hornaday reported that in the 1880S travel
ers on the Great Plains saw gigantic buffalo oxen, animals that had been castrated by wolves but survived to become bison of enormous size.
Isle Royale showed that wolves—and perhaps predators in general—were not what people thought they were. Says Mech, “They have to try very hard for anything they get. And that is contrary to the views of a lot of the public, and contrary to the views of biologists long ago, and contrary to the views of ungulate biologists, who feel wolves can go around and kill any time they want. If people understood the prey’s advantages, there’d be even more sympathy for the predator as being a helpless link in that system.”
At the conclusion of his graduate work, Mech left Isle Royale. A series of other principal investigators—Philip Shelton, Peter Jordan, Wendel Johnson, Michael Wolfe, and Rolf Peterson—continued the study under Allen’s direction. Well into the 1970s, the moose and the wolves continued to thrive on the island, a fact that helped persuade Minnesota and other states to stop paying bounties on wolves. It also helped push British Columbia, and then other Canadian provinces, to stop controlling wolves as vermin and to reclassify them as a game species. Meanwhile, with funding from the World Wildlife Fund and the New York Zoological Society, and later the U.S. Fish and Wildlife Service, Mech began another study of wolves, in northern Minnesota’s Superior National Forest. Today, that and the Isle Royale studies are the two longest-running studies of a wildlife population in the Western Hemisphere, perhaps in the world.
In Minnesota, Mech would see the picture of wolf predation he helped develop on Isle Royale grow more complex. Here deer rather than moose were the prey population. Eight of the ten previous winters had been mild, and when Mech arrived the deer were thriving. But from 1966 to 1972, there were seven severe winters. Deer declined all across the Great Lakes area from 1969 to 1975. Fawn-doe ratios declined in both wolf-inhabited and wolf-free areas, and deer disappeared from the poorest habitat. But Mech found that more does were lost in areas where wolves were least persecuted by humans. He had to concede, “Wolves were one of the main causes of the deer decline in the Superior National Forest.”
The Company of Wolves Page 9