Wolves of Isle Royale National Park

Few animals have been as romanticized and vilified as wolves have, but after five decades of collecting data and studying wolves in the wilds of Isle Royale National Park in Lake Superior, researchers Durward Allen, Rolf Peterson, L. David Mech, John Vucetich and their teams, have greatly enriched our understanding of wolves. Isle Royale is a 200 square mile island in Lake Superior, about 15 miles from the international shore-line boundary where Minnesota meets Ontario. Moose swam to Isle Royale about 100 years ago, and wolves wandered across the ice from the mainland about 50 years later, during a bitterly cold Winter. Warming climate has made it unlikely that more wolves will be crossing over any time soon, so Isle Royale sits out in Superior as a perfect natural laboratory, enabling the longest continuous study of predator-prey relationships in the history of modern science.

The core of a wolf pack consists of the breeding male and female, who generally turn out to be “Mom” and “Dad”, and the pups of the year, who, following the mating in February, are born about 60 days later, towards the end of April or in early May. The other members of the pack are usually older siblings from the two previous years, which are physically mature in terms of size by the time they are 8 or 9 months old, but not sexually mature until sometime between their second and third year. Throw in the occasional straggler absorbed or dispersed from another pack, and you have a wolf pack, curiously similar to a human family.

Older siblings, along with Mom and Dad, protect the pups of the year, and offspring can obtain food by approaching, and nuzzling or licking the muzzle of any grown wolf, which then regurgitates undigested food. Pups begin exploring and wandering from the den after 4 weeks, and, as use of the den lessens, and the pups begin weaning, they are led to kill sites to feed and begin learning the ways of adults. This happens at about 4 months of age, and these "rendevous sites" become the gathering spots for the family.

At sexual maturity, wolves disperse from their packs, seeking to fill a position in another pack, or find an area where the pressure from resident, territory defending packs is diminished, and where they may start their own pack with a dispersing or wandering member of the opposite sex. This leads some young wolves to disperse up to 600 miles away from their natal pack, and explains how wolves spill over into adjoining areas, such as Minnesota wolves spreading to Wisconsin and the upper peninsula of Michigan.  Now and then, the over-abundance of prey animals will result in larger packs, where more than one pair of wolves is mating.
 
Based on computerized skull measurements, wolf taxonomist Ron Nowak distinguishes about 5 North American wolf subspecies, the Arctic, Mexican, Great Plains, Northwestern, and the Eastern Timber wolf, examples of which can be seen in Algonquin Park, west of Ottawa. Your average male wolf is about 90 pounds, with northern wolves slightly heavier, due to natural selection rewarding larger body mass, and its heat retention capability. Cree, a wolf hybrid, of about 75% pure wolf, is 110 lbs., while Zeebie, a full wolf and an example of a Great Plains wolf, is about 100 lbs. The eastern coyote, variously called the Adirondack wolf, brush wolf and coydog, is genetically an eastern wolf-coyote hybrid, which explains why it tends to be twice the size of its western cousin.

Loyalty within the wolf pack is strong, and while you may observe much dominant posturing, snarling and growling by Cree, the gray male, born in 2006, in the role of older brother, and correspondingly submissive behavior by Zeebie, the younger black male, born in 2009, there is no actual violence. Look for Cree to carry himself upright, with his tail slightly cocked and raised in these encounters, and for Zeebie to approach Cree with a lowered posture, with tail down or tucked, while attempting to lick Cree’s muzzle in a sign of deference.
 
Wolves lead very dangerous and risk-prone lives, and any wild wolf is fortunate to reach its fifth birthday. In captivity, with food removed as a daily concern, wolves will live ten to 17 years, much like your dog. Starvation is the number one killer of wolves in the wild, and of predators generally. Other factors include attacks by other wolf packs, usually involving territory infringement and competition for prey, or being injured or killed by intended prey, as when a wolf chooses to attack an underestimated moose under the wrong circumstances. Legal hunting and poaching by man is another major factor in many areas.

The starvation factor is most difficult for us to appreciate, as we live in a culture that provide safety nets, such as medical care, life insurance, unemployment, welfare, savings accounts, etc.  In other words, whether I'm a great provider, or merely an adequate provider, I am protected against the strains of periods when I am less able to provide for my family. While some predators, like foxes and goshawks may cache food, generally speaking, if you're a wolf or other predator, and you follow 8 months of successful hunting with several months of poor hunting, you and your family will likely starve. By definition then, any predator that so much as survives through a given year, is not only a good hunter, but a great hunter, or being supported by a great hunter.

Diseases like parvo virus and distemper take their toll, as do parasitic critters like the mite that causes mange. With respect to wolves from one pack killing trespassers from other packs, or transient wolves passing through a territory at the wrong place and time, breeders may kill 3 or 4 wolves from other packs during their lifetime. Because of frequent turnover in the pack, there are times when an outsider may enter the territory at the right time, and become incorporated into the pack. Wolves also eliminate competition, by killing smaller predators, such as coyotes and foxes, when they encounter them, which enables a larger number of smaller prey animals for the wolves to take.

Incidentally, something to ponder when considering the proposed reintroduction of  wolves to the Adirondack Park: as of 2010, there are an estimated 800 moose within the Park's 9,400 square miles, compared with 500 moose within Isle Royale's 200 square miles. And while moose numbers seem to be increasing at an accelerated clip, there are, on the other hand, probably 80,000 white-tailed deer within the park. When wolves were introduced out west, into Yellowstone Park, Idaho and Montana, they may have eliminated half the western coyote population, and a good percentage of an increasing beaver population, within their territories. Gray wolves kill mesopredators (like coyotes) to eliminate competition for smaller game. But according to DNA studies, the eastern coyote is part wolf, thus accounting for its enhanced size, but the wolf component is mainly eastern wolf, like those found in Algonquin Park, and closely related to the red wolf, which is being reintroduced into the Carolinas with mixed success. This is because the red wolves are interbreeding with local coyotes.

While there is very limited livestock within the Adirondack Park itself, there are livestock farms outside the Park, and the spreading of wolves through dispersal would probably necessitate the control of wolves through hunting, an idea unpopular with many pro-wolf groups, who would prefer no wolves to a recovering wolf population subjected to hunting. Compromise may be a prerequisite to any wolf reeintroduction. David Mech has a 2006 paper, Wolf Restoration to the Adirondacks, and there's a ten year old study on wolf restoration from the Conservation Biology Institute at wolf-reintroduction-feasibility-in-the-adirondack.

Wolf packs defend territories ranging in size from 20 square miles to 2000 square miles, depending on the amount of prey of varying sizes available within their territory, the number of wolves in the pack, and the pressure of adjoining packs defending their territories. Howling is an important means of communication among wolves, both within the pack, for example, to identify location viz a viz another pack member, or as a pack bonding activity, and between neighboring packs, as a means of avoiding confrontations by indicating a pack’s current location. While the packs cover large territories, the boundaries of these territories are somewhat fluid, so, to avoid confrontations with neighboring packs, the pack may only enter the fringe buffer zone in pursuit of prey.

Breeding wolves continually mark their territories by "RLU", raised-leg urination, in males, and “FLU”, flex-Leg urination in females, while submissive wolves, male or female, perform "SQUs", or urinations by squatting. Defecating is another form of marking, as is vigorously scratching the ground with the front paws, which opens the scent glands between their toes, thus leaving their scent as a warning to tresspassers. You will notice on the wolf walk, that Cree growls when covering the scent spot of an unwelcome tresspasser, like a coyote or a dog he does not like. When wolves roll in a scent, it may be a way of carrying information of some discovery back to the pack, so that the pack can decide whether to visit and perhaps appropriate the source of the odor.

On Isle Royale, the principal prey of the wolf are moose, and over the fifty years of the study, the number of resident moose on the island, has ranged between the 500 surveyed in 2009, to a high of 2,500 in 1998, while the number of wolves varied from a dozen to 50, with average being about 20 wolves spread over 2 or 3 packs. In 2010, there were 19 wolves comprising 2 packs, whereas in 2009, there were 22 wolves in 5 packs, in addition to a couple of "floaters", loners who lead furtive lives, scavenging at the edges of territories, either avoiding resident packs, or cautiously trying to assimilate into one pack or another. In 2010, there was estimated to be 510 moose. You may follow the annual reports and articles from Isle Royale at www.isleroyalewolf.org.

While wolf predation is an important contributing factor, particularly when moose numbers are down and wolf numbers are up, moose are also affected by over-browsing of balsam fir, hot summers, deep winter snow, which affects the ability of moose to move around more so than it affects wolves, the amount of infestation by ticks, as well as the mite that causes mammalian mange. Another serious problem for an animal that in maturity consumes an average of five tons of vegetation per year. is the gradual deterioration and breakdown of tooth and jaw. While virtually all older moose sooner or later develop arthritis, a recent important study by Peterson found a correlation between earlier onset of arthritic joints in moose born to undernourished cows. The average lifespan of moose on Isle Royale is 12 years for bulls and 16 for cows, with 20 being the record.

Wolves are affected by starvation, mange, distemper, introduced diseases like parvo virus and inbreeding caused by the fact that the entire wolf population can trace its ancestry to a single female that was one of the first wolves to migrate across the ice from Canada. There has been debate whether to release some unrelated wild wolves on Isle Royale, as an attempt to encourage genetic diversity.

The wolves tend to take mainly older, arthritic or otherwise infirm moose, as well as bulls weakened by exhaustion and the injuries they often sustain during the autumn rut. Calves are another important target, but in 2009, no calves were taken during the winter, there being an abundance of older moose. Once moose reach the age of two, and particularly when they reach the breeding age of five, and until they are nine or ten, they are less vulnerable to wolf attack.

A mature moose in the prime of life weighs anywhere from 1,000 to 1,500 pounds, and is quite capable of defending itself with kicks and, in the case of bulls between May and November, swings of those enormous antlers, so the pack is wary of attacking such an animal, and may test the same moose many times over a period of years, before deciding the moose is one day vulnerable enough to risk an attack. The correlation between the numbers of wolves and moose can have a generationally delayed affect. For example, if over browsing leads to malnutrition in moose calves, which live shorter lives because of earlier onset of arthritis, this will initially provide wolves with greater numbers of older, potential prey animals. In turn, the wolf pups, less apt to starve, survive and breed, but their offspring are then subject to fewer older moose to prey on, causing wolf numbers to crash.

In nature, all events, processes and players are connected. We highly recommend "The Wolf's Tooth", by Christina Eisenberg, which describes the role of predators in "trophic cascades". Wolves are "apex predators", meaning top of the food chain predators, in much the same way as are  loons, fishers and the Eastern Coyote, in the Adirondacks. Wolves are also "keystone" predators, meaning that their impact in a given ecosystem, will have ramifications far beyond the animals they prey on. For example, who suspected that the reintroduction of wolves into Yellowstone National Park would improve the survivability of trout?

Before wolves were reintroduced, elk tended to congregate around the streams, lakes and rivers in Yellowstone, over browsing cottonwoods and willows, while trampling other streamside vegetation, causing erosion, thus making creeks broader and shallower, cutting down the shade which helps keep water at the cooler temperatures trout prefer. As a consequence of wolves reducing elk numbers , creekside vegetation has somewhat recovered, helping the trout, but also, with trees being left to mature, providing nesting sites for song birds, and food, along with den and dam building materials, for the reintroduced beaver, whose numbers increased, even though they are occasionally taken by wolves.

Even pronghorn antelope were helped by the return of wolves to Yellowstone. Cougars and coyotes both prey on pronghorns, with the latter adept at finding young pronghorns. While an individual cougar can handle an individual wolf, the fact that cougars run into groups of wolves makes them reluctant to come down out of the hill country. And while wolves eliminate a third of  the coyotes within their territories, but have so far not yet focused on pronghorn calves as coyotes do, pronghorns have increased since the wolf's reintroduction.

Steve Hall, with editing help and suggestions from Dave Mech