Although most wolves have gray fur, their color may vary from pure white on the Arctic plains to jet black in the subarctic forests.  Wolves howl to warn other wolves to stay out of the pack's territory, they're an endangered species in every state except Alaska and Minnesota.   The wolf is classified as a threatened species in Minnesota.   Most wolves live in packs, but some wolves leave the pack and become "lone wolves."   A lone wolf travels alone until it finds a mate to have pups to form their own pack.