Wild wolves demand three essential things for their survival. The first two are simple: a proper source of food and an agreeable habitat. The third requirement, human acceptance of their presence, or toleration, has proven more complicated.
Because wolves are carnivorous, they require diets that are high in protein. As wolves are considered high level predators - meaning there is no animal above them in the food chain - they depend heavily on large game, such as deer, moose, elk and caribou. In some cases, wolves supplement their diets with smaller prey, such as rabbits or lemmings, and occasionally with garbage and livestock as well.
Regarding their habitat, wolves have proven extremely adaptable throughout the history of the species, acclimating themselves to such diverse locations as tundras, deserts, plains and even temperate rain-forests. As of 2014, the largest populations of wild wolves were clustered in northern regions of Russia and Canada, though some were found in areas as dramatically different in climate as Mexico and India.
The most precarious condition of the wolf's existence is its relationship with humankind. For many centuries, wolves were deemed critical enemies of farmers and raisers of livestock, making them constant targets for hunters. As of the 21st century, with human help, wolf populations are rebounding in significant portions of the globe, even locations were they were once completely or nearly eradicated.