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Fauna Series No. 7







Study Area

Isle Royale Mammal History

Methods and Extent of Present Research


Wolf-Moose Coaction




Fauna of the National Parks — No. 7
The Wolves of Isle Royale
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LESS than a century ago, the timber wolf (Canis lupus) occurred throughout North America, but today it is absent as a resident from 45 of the 48 contiguous States. Probably less than 500 individuals inhabit the remaining three—Minnesota, Wisconsin, and Michigan. Undoubtedly the most important factor leading to the decline in wolf numbers through out most of the country was habitat destruction. Just as a drained pond cannot support fish, a destroyed wilderness cannot support wolves.

However, persecution is also responsible for the present low wolf population. Wolves have been persecuted ever since the first settlers established colonies over three centuries ago. On every part of the frontier, wolves competed with man for prey that man wished to reserve for himself—his livestock—and therefore they had to be eliminated. Trapping, hunting, poisoning, and den-digging, much of this by Government predator-control agents, took their toll. Wolves were not allowed to remain even in remote wildernesses in the West because it was feared that the surplus from these reservoirs would flow into the cattle and sheep country. Persistent harassment of the species thus has resulted in its extirpation from the West, with the possible exception of a small remnant population in the Sierra Nevada of California (Ingles, 1963). Even today, occasional stragglers from Canada are quickly eliminated. Young and Goldman (1944) and Young (1946) have traced the history of the species in North America in detail.

wolves and moose
Figure 1—Wolves holding a moose at bay. Note that the only close individuals are behind the moose. The pack harassed the animal for 5 minutes, then left (see Hunting Account 16). (c) National Geographic Society, courtesy National Geographic Magazine.

The size and habits of the timber wolf probably help make it more of a target for crusading citizens than are other carnivores. It is one of the largest predators, adult weights ranging from 65 to 175 pounds, depending on the subspecies. There are 23 North American subspecies of Canis lupus, the more northern generally including the heaviest individuals. The largest wolf on record seems to be the 175-pound Alaskan wolf reported by Young and Goldman (1944). Total lengths of wolves range from 59 to 69 inches, and shoulder heights from 26 to 38 inches.

The wolf's habits of howling and of hunting in packs no doubt have been important factors in the public's acceptance of the animal as evil-incarnate. Most wolf packs contain less than 10 members, but there are a few authentic records of packs numbering up to 50. Although a group of 50 wolves would be a spectacular sight indeed, some popular writers have not been content to deal even with this large number; they had to create absurdly enormous packs. Thus we get such a fantastic tale as that by Alexandre Dumas in his book Voyage en Russie, supposedly dealing with his trip to Russia in 1859. A translation of certain sections, concerning a wolf hunt, published in Sports Afield (1960), contains the following passage:

Their number increased so rapidly that they seemed to be literally rising out of the earth. There was something uncanny about the way they appeared out of nowhere. It was hard to account for the presence of 2,000 or 3,000 wolves in the middle of a treeless desert where no more than two or three isolated animals could be seen in the daytime.

The anti-wolf prejudice of most of us was instilled when we were naive and innocent tots. One of the first songs many of us learned was "Who's Afraid of the Big, Bad Wolf?", and a few years later we learned the stirring story of "Peter and the Wolf." The plight of "Little Red Riding Hood" and of the "Three Little Pigs" reinforced our view of the wolf as a most undesirable creature. With such priming, how could we have helped believing the perennial tales that used to emanate (and sometimes still do) from Alaska and Canada about the poor soul who had been torn limb-from-limb and devoured mercilessly by some bloodthirsty wolf pack? Such stories often give the full name, address, age, and other detailed information about the victim, but when traced down, these tales prove to be masterpieces of fabrication. Lee Smits (1963) soberly reviewed the subject of wolf-man relationships and concluded that ". . . no wolf, except a wolf with rabies, has ever been known to make a deliberate attack on a human being in North America."

But the wolf is a killer. Nature endowed the species with a type of digestive system that requires meat. Unlike humans, however, wolves cannot push the job of butchering onto a few individuals while the rest of the population righteously looks the other way; they must all do the job. In their present dwindling range, they feed on wild prey almost exclusively. Yet many people feel that the wolf competes with man every time it kills a game animal. On the other hand, most biologists insist that wolves merely take surplus game that man would never get anyway (e.g., Stenlund, 1955). Nevertheless, ruthless persecution continues today. It is generally agreed that the remnant wolf populations of northern Wisconsin and Michigan (except for Isle Royale) probably totaling less than 50, are on their way to extinction. These wolves may not even be breeding successfully. Although Michigan removed its wolf bounty in 1958, it maintains an open season on the species. Wisconsin has not only removed its bounty on wolves but it has even given the species the protection of a closed season. Many people feel it is too late, however, to save the Wisconsin wolves.

There are probably only 300 to 400 wolves remaining in Minnesota, but that State still has a bounty. About the only time a bounty might help decrease a predator population is when the species has a low reproductive rate, when the population itself is low and the bounty payment high, and when there are very efficient methods of capture. Such is now the case in Minnesota. The use of aircraft and snowmobiles have greatly expedited wolf capture. Thus there is genuine concern that unless the bounty is removed, the voice of the timber wolf will soon be silenced in the State that now so rightly boasts of its great wilderness.

With prospects so poor for the timber wolf over most of its present range, it is important that the species be studied while it is still possible to do so. Ecological research on this big-game predator so far has yielded somewhat conflicting theories. Do wolves kill indiscriminately, or are they limited to sick and weak individuals? Do they affect prey populations only incidentally, or do they control or deplete them? What controls a wolf population? What is the function of the wolf in a wilderness area? The answers to these and other questions were sought during the present study of wolf ecology.

Isle Royale National Park in northwestern Lake Superior is an ideal location for such a study. Fifteen miles from the nearest mainland, this outdoor laboratory has supported a discrete population of moose (Alces alces) for about 60 years and of wolves for about 15. No other big-game animal or large carnivore is present, and all wildlife is protected from hunting. Preliminary work by Cole (1957) and others indicated that intensive wolf and moose research on the island would be highly rewarding.

Long before wolves populated Isle Royale, biologists speculated about bow they might affect the moose herd, which had greatly exceeded the carrying capacity. After the wolf population became established, the possibilities for research were apparent to many.

In June 1958, Purdue University initiated the present 3-year study, the first of a series. Essentially, the objective was to explore the dynamics of wolf-moose relationships. Use of an aircraft in winter facilitated gathering the most significant information, but ground observations in spring and summer provided additional data.

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Last Modified: Thurs, Jul 4 2002 10:00:00 pm PDT

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