OccurrenceWolves can live in a variety of habitats, ranging from arctic tundra to forest and prairie, if suitable prey is present. They are absent from deserts and the highest mountains. At one time the wolf occurred throughout most of the Northern Hemisphere north of 20 deg north latitude, or approximately from the Arctic to south central Mexico. Attempts to exterminate the animal have reduced this range considerably. In the Old World wolves still exist in the Soviet Union, China, northern India, and eastern Europe and, very small numbers in western Europe and Scandinavia. Most New World wolf populations are in Canada and Alaska, where they appear relatively stable. A small population exists in Mexico. Of the 48 contiguous states only Minnesota currently has a wolf population large enough to maintain itself. The U. S. government reports that a few wolves live on Isle Royale in Lake Superior and in Michigan, Montana, and Wisconsin; scattered wolves have been sighted elsewhere. Government plans to reintroduce wolves into what was once their native habitat have met with opposition, particularly from ranchers and hunters, who fear the wolves' killing of livestock and game.
Social Behavior
The basic social unit of wolf populations is the pack, which usually consists of a mature male and female plus offspring one or more years of age. Pack size can reach 36, but usually 2 to 8 individuals are present. Each pack ranges over its own area of land, or territory--which may vary from 130 to 13,000 sq km (50 to 5,000 sq mi)--and will defend all or much of this area against intruders. Members form strong social bonds that promote internal cohesion. Order is maintained by a dominance hierarchy. The pack leader, usually a male, is referred to by behaviorists as the alpha male. The top-ranking (alpha) female usually is subordinate to the alpha male but dominant over all other pack members.
When two wolves meet, each shows its relationship to the other by indicating dominance or submission through facial expression and posture. Additional modes of wolf communication are howling and other vocalizations and scent marking. One function of howling is to communicate position or assemble the pack; advertisement of territory to neighbors is probably another. Scent marking involves deposition of urine or feces on conspicuous objects along travel routes, usually by dominant wolves. This behavior appears to function in territory maintenance and in intrapack communication.
During the course of each year wolf packs alternate between a stationary phase from spring through summer and a nomadic phase in autumn and winter. Activities during the stationary phase involve caring for pups at a den or homesite. During summer most movements are toward or away from the pups, and adults often travel and hunt alone.
By autumn pups are capable of traveling extensively with the adults, so until the next whelping season the pack usually roams as a unit throughout its territory in search of prey. In tundra areas wolf packs follow herds of caribou in their annual migrations.