Caribou are relatively free from this predator only during calving time, when the breeding wolves are raising their young in areas distant from the calving ground. A wolf requires food equivalent to, and may kill, 11-14 caribou a year. Most wolves also hunt mice, lemmings, other small mammals, and birds. Wolves cannot run as fast for as long as healthy caribou, especially in deep snow, so wolves often chase a caribou in relays, or wait in ambush for an unwary victim. Wolves have a culling effect on the caribou population, as they kill the aged, injured, or young weak animals when they are available.
Most biologists agree that the relationship between wolf and caribou benefits both.
Certainly the relationship has evolved and lasted over tens of thousands of years. The human being, however, is the greatest of all caribou predators. Many Canadian Amerindians and Inuit based their culture on the caribou, and could not have survived in the north without them. The take by hunters using primitive weapons was in balance with the numbers of caribou. The introduction of the rifle by trappers and traders, however, made it possible to kill large numbers.