Isle Royale

Wolves of Isle Royale


Anchored in the northwest depths of Lake Superior, Isle Royale is one of America’s last remaining wild places. Fifty-six miles of inhospitable waters isolate the island from the Michigan mainland. Explore this wilderness island with wolf biologists Rolf Peterson and John Vucetich, as they attempt to make sense of the delicate balance between wolf, moose and climate.


To learn more about the study, visit John Vucetich’s The Wolves and Moose of Isle Royale Website. For information on the film, contact George Desort.

Isle Royale National Park Information Page


Wolves develop from pups at an incredible rate.  Pups are born, in late April, after just a two-month pregnancy.  They are born deaf, blind, and weigh no more than a can of soda pop.  At this time, pups can do basically just one thing – suckle their mother’s milk. Within a month, pups can hear and see, weigh ten pounds, and explore and play around the den site.  The parents and sometimes one- or two- year old siblings bring food back to the den site.  The food is regurgitated for the pups to eat.  By about two months of age (late June), pups are fully weaned and eat only meat.  By three months of age (late July), pups travel as much as a few miles to rendezvous sites, where pups wait for adults to return from hunts. Pups surviving to six or seven months of age (late September) have adult teeth, are eighty percent their full size, and travel with the pack for many miles as they hunt and patrol their territory.  When food is plentiful, most pups survive to their first birthday.  As often, food is scarce and no pups survive. A wolf may disperse from its natal pack when it is as young as 12 months old.  In some cases a wolf might disperse and breed when it is 22 months old – the second February of its life.  In any event, from 12 months of age onward, wolves look for a chance to disperse and mate with a wolf from another pack.  In the meantime, they bide their time in the safety of their natal pack.

at an incredible rate.  Pups are born, in late April, after just a two-month pregnancy.  They are born deaf, blind, and weigh no more than a can of soda pop.  At this time, pups can do basically just one thing – suckle their mother’s milk. Within a month, pups can hear and see, weigh ten pounds, and explore and play around the den site.  The parents and sometimes one- or two- year old siblings bring food back to the den site.  The food is regurgitated for the pups to eat.  By about two months of age (late June), pups are fully weaned and eat only meat.  By three months of age (late July), pups travel as much as a few miles to rendezvous sites, where pups wait for adults to return from hunts. Pups surviving to six or seven months of age (late September) have adult teeth, are eighty percent their full size, and travel with the pack for many miles as they hunt and patrol their territory.  When food is plentiful, most pups survive to their first birthday.  As often, food is scarce and no pups survive. A wolf may disperse from its natal pack when it is as young as 12 months old.  In some cases a wolf might disperse and breed when it is 22 months old – the second February of its life.  In any event, from 12 months of age onward, wolves look for a chance to disperse and mate with a wolf from another pack.  In the meantime, they bide their time in the safety of their natal pack.From birth until his or her last dying day, a wolf is inextricably linked to other wolves in a complex web of social relationships.  The ultimate basis for these relationships is sharing food with some, depriving it from others, reproducing with another, and suppressing reproduction among others.

Most wolves live in packs, a community sharing daily life with three to eleven other wolves.  Core pack members are an alpha pair and their pups.  Other members commonly include offspring from previous years, and occasionally other less closely related wolves. Pups depend on food from their parents.  Relationships among older, physically mature offspring are fundamentally tense.  These wolves want to mate, but alphas repress any attempts to mate.  So, mating typically requires leaving the pack.  However, dispersal is dangerous.  While biding time for a good opportunity to disperse, these subordinate wolves want the safety and food that come from pack living.  They are sometimes tolerated by the alpha wolves, to varying degrees.  The degree of tolerance depends on the degree of obedience and submission to the will of alpha wolves.  For a subordinate wolf, the choice, typically, is to acquiesce or leave the pack. Alphas lead travels and hunts.  They feed first, and they exclude from feeding whom ever they choose.  Maintaining alpha status requires controlling the behavior of pack mates. Occasionally a subordinate wolf is strong enough to take over the alpha position. Wolf families have and know about their neighbors.  Alphas exclude non-pack members from their territory, and try to kill trespassers.  Mature, subordinate pack members are sometimes less hostile to outside wolves – they are potential mates.

Being an alpha wolf requires aggression, control, and leadership.  Perhaps not surprisingly, alpha wolves typically possess higher levels of stress hormones than do subordinate wolves, who may not eat as much, but have, apparently, far less stress.Pack members are usually, but not always friendly and cooperative.  Wolves from other packs are usually, but not always enemies.  Managing all of these relationships, in a way that minimizes the risk of injury and death to one’s self, requires sophisticated communication.  Accurately interpreting and judging these communications requires intelligence.  Communication and intelligence are needed to know who my friends and enemies are, where they are, and what may be their intentions.  These may be the reasons that most social animals, including humans, are intelligent and communicative.

Like humans, wolves communicate with voices.  Pack mates often separate temporarily.  When they want to rejoin they often howl.  They say: “Hey, where are you guys; I’m over here.”  Wolf packs also howl to tell other packs: “Hey, we are over here; stay away from us, or else.”
There is so much more to wolf communication.  Scientists recognize at least ten different categories of sound (e.g., howls, growls, barks, etc.).  Each is believed to communicate a different, context-dependent message.  Wolves also have an elaborate body language.  As subtle as body language can be, even scientists recognize communication to be taking place by the positions of about fifteen different body parts (e.g., ears, tail, teeth, etc.).  Each body part can hold one of several positions (e.g., tail up, out, down, etc.).  There could easily be hundreds to thousands of different messages communicated by different combinations of these body positions and vocal noises.  Scientists apprehend (or misapprehend) just a fraction of what wolves are able to communicate to each other.
Wolves also communicate with scent.  The most distinctive use of scent entails territorial scent marking
The life of a wolf is largely occupied with walking.  Wolves are tremendous walkers.  Day after day, wolves commonly walk for eight hours a day, averaging five miles per hour.  They commonly travel thirty miles a day, and may walk 4,000 miles a year.
Wolves living in packs walk for two basic reasons – to capture food and to defend their territories.  Isle Royale wolf territories average about 75 square miles.  This is small compared to some wolf populations, where territories can be as large as 500 square miles.  To patrol and defend even a small territory, involves a never-ending amount of walking.  Week after week, wolves cover the same trails.  It must seem very ordinary.
The average North American human walks two to three miles per day.  A fit human walks at least five miles/day.  If you want to know more about the life of a wolf, spend more time just walking, and while walking, know that you are walking.  What do wolves think about much while walking?

Wolves defend territories. About once a week, wolves patrol most of their territorial boundary.  About every two to three hundred yards along the territorial boundary an alpha wolf will scent mark, that is, urinate or defecate in a conspicuous location. The odor from this mark is detectable, even to a human nose, a week or two after being deposited.  The mark communicates to potential trespassing wolves that this area is defended.  Territorial defense is a matter of life and death. Intruding wolves, if detected, are chased off or killed, if possible.
Wolves are like humans for having such complex family relationships.  Wolves are also like some humans in that they wage complete warfare toward their neighbors. An alpha wolf typically kills one to three wolves in his or her lifetime.
Because territories are a pack’s hunting grounds, giving up territory to other wolves is to give up food for the family.  Territories are large enough to contain all the prey that a pack needs. more
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