The territory of an animal is defined as the area that the animal will defend against other animals of its species. This is different from the home range of an animal, which is defined as the area that an animal lives in, but does not defend against other members of its own species. It has been difficult for researchers to determine how territorial wolves really are, since research into that area would require researchers to monitor the movements of an entire pack of wolves for an extended period of time, and determine how it reacts to other wolves in its territory. Since wolf packs rarely encounter each other, such observations are limited. However, in general, it does seem that wolves are territorial creatures. Wolf biologists have observed wolf packs chasing and attacking foreign wolves (see Mech, 1970), and large packs will often chase smaller packs that have intruded onto their territory. Wolves are rarely friendly towards other wolves that are unfamiliar to them, and many of them stay within a well-defined area. A wolf pack's territory will contain most of its hunting and travelling areas. Wolf packs are often spaced out enough so that their territories do not overlap significantly. When territories do overlap, the two or more packs still manage to stay far away from each other.
A variety of factors determines the size of a wolf pack's territory, which can vary greatly from about 18 square kilometres per pack to 1300 square kilometres per pack. Wolves live within small, well-defined territories when prey animals are abundant and when they can stay in one place year round. Wolves generally have small territories in the forests of Minnesota or Ontario. Large territories are found where prey is less common, or where prey may migrate. In Alaska and the far north, wolves have large territories because the prey they hunt there (such as caribou) often migrate and travel hundreds of miles each year. The boundaries of such territories can be difficult to define, and some wolf packs of Canada's Northwest territories do not seem to have fixed territories during the winter, a time during which the wolves must travel long distances to follow migrating caribou herds. In general, the home range of a wolf pack is much larger during the winter than it is during the summer. Other factors that may influence the size of a territory that a pack will defend include climate, the presence of other wolf packs and the nature of the terrain. In areas where there is little suitable wolf habitat and a high density of people, wolves often have rather small territories. Wolves tend to have larger territories in areas where there are many other large predators, such as wild cats and bears, present.
Wolves frequently move into new territories in search of prey, and a pack's territory often expands and contracts in response to the movements of prey animals. Most wolf packs do restrict their journeys to trails and areas they are familiar with, though the boundaries of a wolf pack's territory are rarely well-defined. Wolf packs have been observed travelling very long distances during the winter, and it is not uncommon for one pack to travel over 50 kilometres (about 30 miles) in one day. Wolf packs usually travel in single file, and are usually on the move constantly, except during the breeding season.
Lone wolves do not have territories and often travel amazing distances in search of a mate (see Van Tighem, 1999). For example, a wolf named "Opal" who was radio-collared in Kananaskis country (which is in the Alberta rockies) was found later in Idaho, just North of Yellowstone. She had travelled well over 1000 kilometres from her natal area. A wolf named "Pluie," who was caught and radio-collared in central Alberta, travelled over an area of 100 000 square kilometres. After she was radio-collared, she travelled to Banff, joined a pack there, then left the pack, travelled through British Columbia's flathead valley, headed down to Idaho, and then travelled back to Banff. That was all during a three year period. Later, her radio-collar was found several hundred kilometres south, just North of the Waterton-Glacier International Peace Park. The researchers lost track of Pluie, until she was found later near Invermere, British Columbia. Sadly, she had been shot by a hunter.
Wolves use many methods to define their territories. In territories that are well defined, the most important method wolves use to mark out their territory is scent marking . Wolves use urine to mark out their territory, and wolves can differentiate the odour of their packmate's urine from a foreign wolf's urine. Wolves have excellent senses of smell, and when a pack ventures onto a territory that has been marked by other wolves, the pack will either leave or risk a fight. Wolves are rarely tolerant of foreign wolves, although R.D. Lawrence, in his book, Trail of the Wolf, does describe a few instances of friendly relations between two different wolf packs.
When a wolf marks its territory, it will raise one of its hind legs and will squirt a small amount of urine on a scent post (usually a raised object like a tree, rock, or bush). This raised leg urination (RLU) is different from ordinary urination, where the wolf will squat on the ground. RLU is usually only performed by alpha wolves (both male and female) although it is usually the alpha male that most commonly performs RLU's. The alpha female usually marks on a scent post that her mate has just marked, although during breeding season, the female may urinate first on the ground. All other females in the pack, as well as low ranking males and young wolves, will squat when they urinate, although exceptions to this rule sometimes occur. Candace Savage, in the book, The Nature of Wolves, mentions that all of the wolves in a pack sometimes mark a certain spot, and that when this occurs, the wolves will wait in line for their turn to mark the spot. Lone wolves almost never perform RLU's so packs do not discover their presence.
High ranking wolves will leave urine marks about every 350 meters when they are marking out their territory. Wolves will also mark the same scent post over and over again. It is sometimes claimed that wolves scent mark to mark out the boundaries of their territories, although some authors (see Lawrence, 1997) claim that wolves do not scent mark to mark out territory boundaries, since the boundaries of a wolf pack are rarely clear and rigid. Instead, wolves may scent mark simply to alert other packs that there are already wolves in the area. The scent marks are like "No Trespassing!" signs for wolves.
Wolves will often place scent marks on spots where other wolves, coyotes, foxes, skunks, racoons, moose, deer and other animals have left marks of urine. Domestic dogs often do that as well. It seems that the scent of any animal on a spot stimulates a wolf to add its own mark to the spot.
A wolf may also rub its lips and neck on a tree or against the ground to mark its territory, and wolves often scrape their paw pads on the ground (usually after they urinate) to mark a territory. This releases odours from the glands in the wolf's paws. Wolves also howl to warn other wolf packs that they have entered foreign territory. Wolves will often answer the howls of another wolf pack. However, wolves will remain quiet if there are pups present so they don't attract attention to the pup's whereabouts. Wolf pups are vulnerable to attacks from large predators, such as bears or mountain lions.