Some more insite into Wolves that you won't hear in the Animal Planet.
Everyone knows Wolves are territorial. A pack has a set territory and will not tollerate another Pack or Wolf invading their turf. It will be a fight to the death many times. Well that is true in areas where plenty of game abounds, like in Yellowstone, Wyoming, Montana, Idaho, and areas where you have lots of Deer and other game.
Now come to Alaska. In the Alaska Range the Wolves are Territorial as well. The Caribou pass through and the Wolves in the area feast while the Caribou last. Then they go back to Moose, Non-Migratory Caribou, and small game. But then move to the 40-mile country, and areas north of there. There is not much up there on the Tundra for a pack to subsist on. They follow the Caribou, year round. In the winter the Caribou move into Canada, the Wolves follow. The Caribou move back into Alaska in the spring, the Wolves follow. Where the Caribou goes, so does the Wolves. The North SLope herd, The Porcupine herd (the herd in ANWR), and the 40 mile herd, all move to Canada then back to ALaska. The wolves follow. In winter they single out an animal and make a kill, any animal will do. Old, young, healthy, or not, does not matter, its all meat. In the spring they follow the herd back west into Alaska. stragglers are the preferred victums. Make a kill and move on before the herd leaves them behind. It's too hard to kill healthy strong running animals now when on the move. Then Calving starts, and calves are the target. Also cows giving birth and unable to run away. Kill the cow and get the calf as a bonus. Then the packs gains strength and no longer needs to conserve strength, so they take any animal they set their sights on. Their territory is where the Caribou is.