Book excerpt: The Yukon wolf is the largest race of Canis lupus in the world. There are 5,000 wolves in the territory. Wolves live in all Yukon mountain ranges hunting Dall's sheep and caribou in the high alpine. In the forested valleys they hunt moose, the ideal prey size for packs to handle. Regional wolf numbers depend on the number of moose in the area. Packs are territorial except in the far north where wolves migrate long distances to follow the Porcupine caribou herd year-round. --From book cover.