Wolves are the largest members of the dog family.The Grey Wolf is known as the Timber Wolf in North America and the White Wolf in the Arctic, or more generally as the Common Wolf.Wolves are legendary because of their spine-tingling howl, which they use to communicate. A lone wolf howls to attract the attention of his pack, while communal howls may send territorial messages from one pack to another. Some howls are confrontational. Calls may be answered by rival packs. Much like barking domestic dogs, wolves may simply begin howling because a nearby wolf has already begun.There are many subspecies of wolf including the Arctic wolf, all of which use a variety of howls to communicate to one another.They have a highly organised social structure enabling them to enjoy maximum cooperation when hunting, communicating and defending territory.Wolves live and hunt in packs. They are known to roam large distances – as much as 20km in a single day. Wolf packs in the far North often travel hundreds of kilometres each year as they follow migrating herds.Wolves are highly territorial animals, and generally establish territories far larger than they require to survive; in order to assure a steady supply of prey. Territory size depends largely on the amount of prey available: in areas with an abundance of prey, the territories of resident wolf packs are smaller.