I remember reading an excellent Farley Mowat book where he spent 6 months in the arctic living next to a wolfpack and studying them. One lovely story he told was about the day he watched the pack moving through a valley full of migrating cariboo, the cariboo all kept just enough distance to be safe as the wolves moved through but other than that were totally unstressed...just like watching a fox work a field with rabbits in I gues. Anyway when the wolves had passed through Farley who had watched this from a ridge above the valley stood up whereupon the whole cariboo herd stampeded over the far ridge...they knew who was to be feared.
Edit just found this on wikipedia on mowat
Having been trained as a biologist, Mowat took a Canadian government job as biologist in the Arctic. At the time, the government was concerned that the size of caribou herds was shrinking, and they suspected that wolves were eating the caribou, so the best way to protect the caribou would be to kill wolves. Flying into the heart of the wilderness on a small plane, Farley set up an observation camp near a local wolf population. After months of observation, Mowat concluded that, contrary to the ranchers' claims, the wolves mainly ate field mice and only ate old or sick caribou — by killing off the weakest of the caribou, wolves actually strengthened the caribou herd. The trappers in the area were, according to Mowat, using the wolves as scapegoats for the decline of the animals, for which they themselves were responsible; one Inuit trapper, who helped Mowat in his observations, estimated that he personally killed three hundred caribou per year to feed his dogs and himself. Mowat set forth his findings in his 1963 book, Never Cry Wolf, a book which was widely read around the world, and which was one of the major reasons the Soviet Union banned the killing of wolves.