Pack (canine)
Animals which typically predominate over others are associated with the term "alpha". Among pack-living wolves, alpha wolves are the genetic parents of most cubs in the pack. Such access to mating females creates strong selective pressure for intra-sex competition.
Wolves and moose on Isle Royale
Wolves on the island have, historically, been separated into three or four packs, with each pack usually having between three and eight members, including two or three pups. The number of wolves in a pack depends mainly on the amount of snow that fell in the previous winter. In winters with light snow, pups tend to leave the pack to find mates, so packs run at four or five members; in heavily snowy winters, the pups stay with the pack, which can reach ten to twelve members. If many members of a pack die, the pack dissolves and a new one forms within a year. One pack will dissolve about once every thirty years.