By now it should be clear that a pack or group of social canids is a collective stomach in search of food. Wolves and free-ranging dogs feed by hunting and scavenging. As defined here, hunting is the act of finding, pursuing, catching, and killing prey, scavenging the act of feeding on carcasses or separating edible components from human refuse and other mostly inedible materials. Both terms are covered by foraging.

Foraging has the obvious benefit of supplying nutrients from which animals gain energy required for growth, reproduction, respiration, generation of body heat, and all other physiological processes driven and controlled by what we call “life.” However, it also has a cost, measured as the energy used to secure food. African wild dogs often chase prey for several kilometers at sustained speeds of 48 kilometers per hour, a tremendous energy expenditure culminating in a burst of strength and effort needed to bring a large ungulate to the ground. Tundra wolves commonly leave the den or rendezvous site (Chapter 8), travel 25–30 km, make a kill, and return with large portions of meat to feed pups and the breeding female all in a matter of hours. Not every hunting trip is successful. If more fail than succeed – that is, if cost exceeds benefit over time – the eventual end is starvation and death. Although wolves can be opportunistic foragers they are primarily hunters of large herbivores. Energetic constraints force them to be. A body mass of 21.5 kg is the point at which carnivorans generally shift from small to large prey, and wolves cross that line. The transition is abrupt: carnivorans smaller than 21.5 kg feed mainly on prey <45% of their own mass, those larger than this select animals >45% of their own mass.