Wolves are among the most social animals in the world. They live in packs which are generally extended families. Pack composition can include the parents, the offspring of various ages, and aunts and uncles of the young. Pack size is governed mainly by the availability of habitat and the food found therein. Wolves are at the top of the food chain thus the size of wolf packs is determined by the amount of prey they depend on, not the other way around. Numbers of prey animals are governed by ecological factors such as the plants they eat.

Pack members cooperate to maintain territories, obtain food and rear young. Packs maintain and protect territories from other wolves by howling, direct confrontation of trespassing wolves, and by scent-marking.

The wolf's co-operative nature is most strikingly demonstrated in pup rearing. Virtually all pack members contribute in raising pups. Pups are born in the spring in underground dens. Both sexes dig dens although it is usually the mother who digs most. Wolves often return to a favoured den site year after year.

In the weeks before pups are born other adults will feed pregnant females by carrying or regurgitating food to her. They also feed her when she is nursing pups in the den.

The mother spends most of her time in the den with pups for the first week, then gradually extends the time she spends away from them. If more than one litter is born all pups which survive are usually put into one combined litter and are tended and nursed by all mothers. Unmated females or females which lost pups can also nurse pups. When more than one female is in the den at the same time, they are sometimes aggressive to each other but never to the pups. There seems to be some competition among the females for access to pups no matter which female's they are.

Pups are born with eyes and ears closed and weighing about a pound. Neonatal pups are unable to regulate their body temperatures well and depend on the mother for much of their warmth. This is one reason feeding of the mother by the other pack members is important. If the mother has to spend a great deal of time hunting for food she might not be able to spend sufficient time huddled with and nursing the newborn pups.

The pups develop rapidly and begin to venture out of the den at about three weeks of age. At this time the other pack members, including adult males and yearlings, begin to feed pups solid food. The mothers are seldom fed after the pups emerge from the den. By this time, the mother often leaves the pups alone or with another adult or yearling while she hunts for food. Yearlings are somewhat intermediate in that they are fed by adult pack members but also feed pups, presuming there is enough food.

The period when the young pups emerge from the den and are getting to be highly mobile is to most observers the most exciting time to watch wolves. This is when the wolf's co-operative and friendly nature is most strikingly demonstrated. All pack members seem to greatly enjoy playing with and caring for pups.

At the Canadian Centre for Wolf Research, the wolves are well provided for so getting enough food is not a problem for the adults and yearlings feeding the pups. In the wild this is frequently not the case. Roughly only about 50% of pups born in the wild make it through their first year. The adults and yearlings are simply not able to obtain enough food to feed them all or they lose pups to disease or accident.

It is a popular belief that the yearlings baby-sit or guard pups while the adults are away. The biologist Fred Harrington studied a pack of radio-collared wolves in the wild and monitored the time individual wolves spent at the den. As expected, the yearlings did spend more time at the den than the adults but Harrington suggests there is more than one interpretation to their behaviour. Yearlings are known to feed pups when food is plentiful. However, if there is insufficient food they might be staying at the den to compete with pups for food brought back by returning adults. The adults face difficult choices in seasons when there isn't enough to go around. From the standpoint of pack survival it would be better for the adult to feed a yearling who has made it through the crucial first year than a pup who stands a strong chance of not even surviving its first year.

DISPERSAL
Perhaps the greatest adventure in any wolf's life is the time of dispersal, or leaving the pack to find a new place to live. Often wolves disperse as yearlings, sometimes not until they are several years old and some never leave home but stay in the territory where they were born. Sometimes they make several journeys in different directions and come home again before leaving for good.

No one knows for certain why wolves disperse. For some, it seems to be a decision to make a new life. Others are driven out of the pack. One thing is certain though and that is being a lone wolf is a dangerous condition. Lone wolves lead a precarious existence and often trail other wolves, always looking for a chance to once again be part of a pack.

DOMINANCE HIERARCHIES
The sociobiologist Richard Alexander has said that one's closest ally is oftentimes also one's fiercest competitor. Wolves compete for rank within the pack, for mates, and in times of scarcity, any necessary resources such as food. Wolves which lose in such competitions can be driven out of the pack or even killed.

Wolf social organization, like most animal societies. is based on dominance hierarchies. The concept of dominance hierarchies was first formulated by a Danish scientist, Thorlief Schelderup-Eppe, in the 1920's. He observed barnyard hens and noticed that they had hierarchies of who could peck whom, or "pecking orders". These hierarchies are not necessarily linear but all have a single dominant hen. We recognize wolf hierarchies, or rank orders, by the postures individual wolves display to each other in some social interactions. A dominant wolf has an erect posture, with ears and tail up. A subdominant wolf lowers its body, tucks its tail and puts its ears back. Wolf packs have two separate hierarchies--male and female. Aggression is generally directed toward same sex wolves.

Some researchers have speculated that dominance hierarchies serve to maintain order and conserve energy within the pack by reducing aggression. It saves wolves fighting seriously each time they contest something. One thing to keep in mind when thinking of wolf social organization, however, is that it is always changing. It is something like politics in that there is always a contender for the dominant position no matter how long the incumbent has been in power. To quote a political adage "the day you are elected is one day closer to leaving office". It is also important to bear in mind that aggression comprises only a small part (about 20%) of wolf social behaviour and seldom results in physical injury. One the pioneers of wolf biology, Adolph Murie, spent hundreds of hours observing families of wolves in Mt. McKinley, Alaska in the 1940's. He observed many interactions between wolves and only one was aggressive. Murie wrote that his greatest impression of wolf social life was how friendly they were with each other. More than fifty years later his words are still true.