In Praise of Wolves

by R. D. Lawrence

  It is currently supposed that moose first arrived on Isle Royale at about the turn of the century, colonizing the island and slowly building up their populations. Present also were coyotes, beavers, snowshoe hares, mice, and, of course, many birds, including waterfowl and grouse. In 1940 the island was declared a national park and as such became the responsibility of the National Park Service, whose biologists came to realize that moose populations were undergoing periodic highs and lows, with numbers building up beyond the point where the food resources could sustain them. Soon after attaining such peaks, moose populations crashed, after which the vegetation began to recover, and the moose numbers started to rise slowly. In due course, the cycle was repeated, a circumstance that caused much concern to men such as Victor H. Cahalane and Durward L. Allen, the former being at the time the chief biologist of the National Park Service and the latter the assistant chief of the Wildlife Research Division of the Fish and Wildlife Service.

  During the late 1940s, rumours began to reach Washington that wolves had somehow gotten to Isle Royale; their possible presence was often discussed by Cahalane and Allen, both of whom hoped that the reports were based on fact, for such an event would probably lead to a more stable moose population and would also offer a wonderful opportunity to research predator-prey relationships in a habitat undisturbed by human hunting, logging, or mining. Then, in 1951, Cahalane showed Allen the cast of a large canine footprint that had been made on the island. It was confirmed as the track of a wolf. As Durward Allen expresses it in his book, The Wolves of Minong (Boston: Houghton Mifflin, 1979): “Both of us were delighted, since this event introduced the greatest of all experiments in predator-prey relations. Potentially, at least, the wolves could build up, stabilize the moose herd, and bring some protection to the vegetation. It was the pattern of primitive times, now to be replayed in a world where such patterns are confused and obscured by the almost universal hunting of moose and the wiping out or heavy control of wolves.”

  Since the Wildlife Research Division of the FWS was the appropriate agency to initiate and take charge of research on the island, Durward Allen and his chief, Logan J. Bennett, sought to obtain funds for the program, but cutbacks were made in the financing of the Fish and Wildlife Service. Wildlife research was not at all popular at that time. Allen, however, did not give up. In 1954, he left the FWS to become executive director of the Pennsylvania Game Commission, which, a year later, he left to join the staff of Forestry and Conservation at Purdue University, in West Lafayette, Indiana. While there, as he says in his remarkable book, he had “a growing idea there was another route to follow in getting something done on Isle Royale.” That something was a determined effort made by Durward Allen to raise funds for island research. His commitment and hard work produced the desired results in 1957, when he was appointed “director, fund raiser, field assistant, and chief cook in the winter camp.” Since that time, research has continued on Isle Royale, spurred from its inception by the indefatigable efforts of Durward Allen, a biologist who had the foresight to anticipate the importance of this work and whose determination would not allow him to take no for an answer.

  When Dr. Allen decided to step down as director of the Isle Royale research project, he handed the reins to Rolf Peterson, a young biologist who had graduated from the University of Minnesota at Duluth, and had completed his requirements for a PhD. with a dissertation entitled “Wolf Ecology and Prey Relationships on Isle Royale.” But between the project’s original director and its current head, a number of other biologists have won their doctoral or postdoctoral spurs on the historic island, including David Mech, 1958-62; Philip C. Shelton, 1960-64; Peter A. Jordan, 1966-69; Michael L. Wolfe, 1967-70; and a more recent crop of research assistants who have worked or are working under Rolf Peterson.

  Although there is no actual proof available, it is generally believed that the wolves which colonized the island in the 1940s were from Ontario, probably from the area south of Thunder Bay, on the northwestern shores of Lake Superior, at which point the northwest portion of Isle Royale is only eighteen miles from the Canadian mainland. It is thought that before a breeding pair crossed over heavy ice to become established in the American national park, several lone wolves may have preceded them at different times, but whether any of these were present on Isle Royale when the colonizing pair got there is an open question. However this may be, in 1952 it was decided to release four semi-socialized wolves on the island, the leader of which was Big Jim, a ninety-five pound wolf whose sire was from Michigan and whose mother had been born in Saskatchewan, Canada. The release was ill-fated. The four wolves appeared to be unable to settle and, semi-tame as they were, molested some of the few settlers that remained in the park, tearing laundry off the lines and apparently acting in a threatening manner. Three of these wolves were shot and killed by park rangers, but Big Jim escaped and may have survived to intermingle with the Canadian wolves.

  In any event, wolves did become established on the island, and as their numbers built up, they formed packs. The moose seemed to stabilize, and it was thought that a balanced predator-prey relationship had at last been attained, replacing the cycle of moose highs and lows. Nevertheless, it appears likely that the wolves could not at first increase at a rate sufficient to maintain a true balance as the moose continued to make small but significant gains during the next fifteen or so years. By 1970, 1,200 moose were clustered on the island. Food shortages occurred. As the browse dwindled, so did the moose.

  By 1977, only some five hundred moose remained after a crash that was largely the result of malnutrition and stress-related ailments rather than of direct predation, although this did, of course, have some effect.

  During the time in which moose numbers had been increasing, the wolf population also continued to grow, in normal response to the law of nature (and physics) which states that for every action there is an equal but opposite reaction. This is now rarely observed in most wilderness areas of the Northern Hemisphere because man’s heavy hand continues to upset the balance, but in undisturbed region – such as Isle Royale – the law maintains animal numbers at levels compatible with the food supplies.

  Under what may be termed normal environmental conditions* in undisturbed environments, all animals gradually experience population increases. But when any one species increases its numbers to the point where these become a threat to the local environment, a variety of factors combine to produce die-offs – as will be noted. And if, at this time, such a population is faced by a number of severe winters, it will eventually crash dramatically.

  Predators respond to periods of plenty by increasing their own numbers. They continue to prosper during and after a crash. Later, when they have picked clean all the carcasses of those animals that have died, there are yet many prey animals left that have just managed to hang on to life. Many are likely to be suffering from diseases, such as arthritis, or are old and generally impaired. Thus, for some time after a major die-off, wolves and other hunters continue to live well, their numbers either remaining constant or actually increasing. Eventually, however, the predators are left with a group of survivors that came through the crash because they were the fittest and most dominant of their kind. These animals are hard to get. While the hunters have been busy cleaning up the carcasses and pulling down the unfit, these hardy individuals have enjoyed abundant forage and have become even fitter. As a result, their offspring are also strong and healthy and much more difficult to kill. The predators then face similar population reductions to those that affected their prey, and for the same reasons.

  Rolf Peterson’s research during the last decade strongly suggests that wolf populations crash about ten years after the prey species reaches the low point, at least on Isle Royale, while the interval between high and low numbers appears to be between twenty and thirty years.

  During the 1960s wolf numbers on the island remained remarkably stable at about two dozen animals, and moose numbers continu
ed to rise despite predation. In the last ten years, however, major fluctuations have been noted among both species.

  In 1970, wolf populations were relatively small, but moose and beaver – the latter an alternate prey animal during summer – climbed to their highest levels in twenty years. Then, in the early 1970s, a number of severe winters affected the moose, which, as noted, numbered about 1,200. At this period, there were about twenty wolves on the island.

  The first die-off of moose occurred during the winter of 1971, when the population dropped to nine hundred. Two years later the animals made a small comeback, increasing by about one hundred. Wolves also increased slightly, to twenty-three. In 1974, moose numbers fell again, then climbed marginally. The wolves continued to increase.

  In 1977 the moose really crashed, their numbers dropping to about five hundred. Before this, the wolves had climbed to forty-four, then dropped to thirty-five. After the moose die-off, the hunters began to increase steadily, reaching a peak of fifty in the summer of 1980. These were divided into five packs, the members of which respected each other’s territories.

  The following winter, however, the wolves began to decline rapidly, falling by 72 percent, to fourteen, by the spring of 1982. In his 1981-82 Isle Royale research report, Peterson comments on the die-off. In his summary, the biologist notes:

  Two years ago, the record-high wolf population of 50 included five territorial packs, with territory boundaries generally honoured. Food stress was obvious, however, and pack size was steadily declining. A year later, with 30 wolves present, the food situation seemed no better and packs often trespassed into neighbouring territories. In 1982, only 14 wolves remained, and the dominant pack of four wolves claimed almost the entire island. Three other breeding pairs and four single wolves were found, but these were actively tracked and likely chased by the dominant “Gang of Four.” We surmise that direct killing of wolves by other wolves contributed to the rapid decline, although we found no dead wolves in 1982. We witnessed a complete turnaround in wolf food availability in 1982, and all groups of wolves had ample food.

  Changes in the moose population, probably prompted by the wolf decline, were no less dramatic. Swelled by almost 200 calves, the moose population increased to over 700 in 1982. A substantial rebounding of moose is certain if subsequent cohorts of calves match that born in 1981.

  If wolves exhibit a moderate rebuilding of numbers within a couple of years, as we expect, this predator-prey system should soon approximate that described 25 years ago. Accumulating evidence suggests that we are witnessing a predator-prey cycle with an extended period of fluctuation.

  That was more or less the situation existing on Isle Royale when George showed us the film of Rolf’s interview. As I listened to the biologist’s words, I made some notes within the projection-room gloom of George’s quarters, covering one small page of a notebook. The first note was prompted when Peterson told his interviewer that the island’s old moose, born during the 1960s were the most numerous victims of the population crash. Practically all of these were suffering from severe arthritis, some of them so seriously that the ball of each femur and both hip sockets were badly worn. These animals, naturally, were easy prey for the wolves, for besides being incapacitated by the disease, they were also undernourished. Indeed, many of them died naturally, furnishing large amounts of food for the wolves. My interest in arthritis stemmed from the fact that my own stress research showed that this condition, if not actually caused by severe stress, was most certainly aggravated by it; then, too, there is evidence suggesting that a combination of stress and malnutrition will considerably speed up the deterioration of arthritic joints. Yet Rolf, with the scientist’s caution, had not referred to stress during his interview. I surely wanted to talk to him about that subject! A little later, I again made a note in reference to stress. This was when Rolf described the wolf decline that followed the moose crash. This time I wrote:

  “Wolves killing each other! They’re at war! Stress must be involved. First time ever that wolves have been known to wage war like people. Talk to Rolf”

  When I had finished outlining the history of Isle Royale to Sharon, it was late, but I was far too excited to sleep. For more than a quarter of a century I had been amassing evidence that pointed directly at stress as the major biological factor in the decline of all species, including humans. My evidence suggested that stress was responsible for man’s most unnatural habit of waging war. Now, for the first time in biological history, a nonhuman animal had evidently engaged in serious and prolonged internecine combat. I was well aware, of course, that wolves on occasion kill each other, as do most other animals, but such killings are uncommon, usually taking place during an accidental clash between a pack and a lone wolf that has strayed into forbidden territory or, more rarely, during status fights, when one wolf challenges another and the loser, for one reason or another, cannot escape after its defeat. But the wolf war on Isle Royale was the first example of what may be termed organized and prolonged hostilities.

  Accompanied by George and Jim Wuepper, we left Marquette during a snowstorm to drive the one hundred miles to Houghton in our station-waggon, stopping on the way to pick up Kirsten Raisanen, a high school biology teacher who is also interested in wolves and in the Isle Royale developments. At Houghton, we met Rolf Peterson in the university cafeteria; following introductions, the biologist gave us a rundown of the developments between wolves and moose.

  After Rolf had brought us up to date, he and I discussed stress, population cycles, and, above all, the incidence of arthritis in those moose born during peak populations in the 1960s, finding much common ground during our exchange. For my part, I was particularly encouraged to find in Rolf a biologist who has devoted fourteen years to field observations of wolves, who is not engaging in esoteric, captive-wolf experimentation, and who has broadened his outlook beyond the confines of his speciality. There are, of course, others engaged in wildlife research who also look beyond the narrow limits of their particular interests, but it appears that these are in the minority. This is a pity, for whatever major discoveries are still to be made – and I believe there are many – will not yield their truths to the single-minded specialists.

  During our interview in Houghton, Rolf had not yet completed his 1982-83 Isle Royale report, but he sent me a copy some time later. It showed that the forecast he had made a year earlier was completely on target. The moose populations had continued to recover from the low level reached in the late 1970s, while the sudden crash of wolf numbers was reversing itself, with predator populations having climbed to a level comparable to that which had existed in the 1960s. These things, as the report noted, were consistent with “our hypothesis of long-term cyclicity in this island’s predator-prey system.”

  Findings on the island up to 1985 continue to support Rolfs hypothesis, the evidence suggesting that the time span between low and crash-high levels of population averages about twenty-four years for each species, the prey animals declining first and the predators crashing eight to ten years later, a thesis that is further supported by the snowshoe hare-lynx data provided by the Hudson Bay fur-cycle records, although in that situation the time span is shorter because both the prey and predatory species are smaller and, additionally, the hares are far more prolific than the moose.

  In July 1985, Rolf sent me his latest research report ( 1984-85). It shows that the wolf population has changed little from a year earlier, but the moose have increased considerably, now numbering 1,062 individuals. This means that during the last four years, the moose population has grown by between four hundred and five hundred since its low point in 1981.

  The wolf population (twenty-two individuals) remained separated into three packs, but it appeared that only two of these had young in 1984. Overall, one pack increased. one declined, and one remained the same, but the survival rate of those wolves present in the winter of 1984 was estimated at 62 percent, which Rolf Peterson believe
s to be low for a protected species. Beaver also increased between 1982 and 1984. These figures confirm that wildlife populations invariably return to a steady state following highs and lows if they are left undisturbed by humans. In my view, Peterson’s report also shows that wolves are not the cause of species decline. Indeed, the wolf is a balancing factor, an animal whose numbers are also controlled by natural forces when they reach a peak.

  During the years in which I have been studying stress, the evidence I have gathered leads me to postulate that there is a definite relationship between overpopulation and severe physiological-emotional stress, and that all species of animals, including our own, are affected by this syndrome. More to the point, perhaps, is that stress appears to be the principal agent by which nature reduces any population whose numbers threaten to unbalance the steady stare of a climax community, whether such unbalancing occurs because of man’s alteration of the habitat or because a species has in some way increased its numbers beyond the carrying capacity of the food supply. Under normal, undisturbed conditions, and within the strictures of natural economy, “bumper crops” are tolerated only after a species has undergone a major decline.

  When any population begins to threaten the balance of its community, but long before its numbers have reached the crash point, the effects of even modest overcrowding cause individuals to become more than usually competitive in all aspects of their behaviour. Levels of tolerance are dramatically reduced and general restlessness develops. Intraspecific aggression is heightened, social bonds are weakened (and it should be noted that all mammals are social to a greater or lesser degree), and each animal becomes negatively self-oriented.