An alpha male and female lead each wolf pack and are the only ones that mate. Wolf packs have a clear hierarchy with alphas at the top and other wolves falling below in status. Wolf pups are born blind and deaf but can walk after 2 weeks; they emerge from the den at 3 weeks old and play fights to establish their place in the pack hierarchy. Wolves communicate through howls to contact other packs or call back pack members, and howl in sadness when a mate dies. Wolf diets vary by region but consist mostly of large prey like moose, caribou or musk ox, though they may occasionally eat smaller animals. The whole pack helps raise and feed the pups.