Highly social and intelligent, the grey wolf is an efficient predator, capable of working together with other individuals to bring down large prey, ten times the size of an individual wolf (5). This species is most commonly found in packs, particularly in winter, usually numbering around 5 to 12 related individuals, although pairs and lone wolves also frequently occur (2) (5). Within the pack there is a clear dominance hierarchy, with the breeding pair possessing a strong, year-round pair bond. The breeding pair dominates the rest of the pack, which are usually the offspring (2). Packs may range over territories spanning 75 to 2,500 square kilometres depending on prey density. In order to advertise territorial boundaries and avoid encounters with other packs, grey wolf packs employ scent-marking and howling (2) (5). On occasions when packs meet violent fights occur, often resulting in fatalities (5).
While grey wolves have a varied diet, prey mostly comprises large ungulates, such as moose, caribou, deer, elk and wild boar (1). Smaller animals, livestock, carrion, berries and refuse may also be taken (1) (5). Prey is hunted down and often pursued in a chase which can last between 100 metres and 5 kilometres (2). The grey wolf’s keen observational skills enable packs to identify and single out individuals that are young, old or in poor condition (2) (5). Attacks usually focus on the rump of larger prey and on the head, shoulders, flanks and rump of smaller animals. On average, the grey wolf consumes 2.5 to 6.3 kilograms of food per day, and will cache surplus food in the form of prey parts or regurgitated chunks (2).
The grey wolf breeds between January and April, with the exact timing depending on latitude (2). Unless food is particularly abundant, only the dominant pair will breed, with the reproduction of other mature females suppressed by aggression and direct interference with copulation attempts by the dominant individuals (3). The dominant female bears a litter of 1 to 11 offspring (typically 6) in the spring after a gestation period of 9 weeks (2). The cubs are raised in a den located in a hole, cave, pit or hollow log, and are weaned at 8 to 10 weeks old. Starting at about three weeks of age, prey parts and regurgitated scraps are provided (2). If food is plentiful, the cubs are ready to travel with the pack at five months old, and by the next breeding season most juveniles leave the pack and disperse (6). Reproductive maturity generally is reached at 22 to 46 months, and lifespan in the wild can reach up to 13 years (6).