The Wolf Pack
Wolves function as social predators and hunt in packs organized according to a strict social hierarchy and led by an alpha male and alpha female. This social structure was originally thought to allow the wolf to take prey many times its size. However, emerging new theories suggest the pack strategy has less to do with hunting than with reproductive success.
The size of the pack may change over time and is controlled by several factors, including habitat, personalities of individual wolves within a pack, and food supply. Packs can contain between two and 20 wolves, though an average pack consists of six or seven. The hierarchy of the pack is relatively strict, with the alphas at the top and the omega at the bottom. The hierarchy affects all activity in the pack, from which wolf eats first to which is allowed to breed (generally only the alpha pair).
New packs are formed when a wolf leaves its birth pack and claims a territory.
Lone wolves searching for other individuals can travel very long distances
seeking out suitable territories. Dispersing individuals must avoid the
territories of other wolves because intruders on occupied territories
are chased away or killed, a behavior that may explain wolf "predation"
of dogs. Most dogs, except perhaps large, specially bred attack dogs,
do not stand much of a chance against a pack of wolves protecting its
territory from an unwanted intrusion.
A wolf pack baiting an American Bison.
Information from wikipedia.com