Gray wolves tend to be opportunistic feeders, but they mainly hunt deer, caribou, moose, elk, bison, sheep and other medium-to-large mammals. Their diet varies depending on what is available. Gray wolves also typically prey on small mammals (such as rodents), reptiles, birds, fish and large insects. When necessary, gray wolves use fruits and vegetables to supplement their food intake.

Gray wolves usually hunt in packs of six to 10 wolves. Cooperative hunting allows them to successfully kill large animals. Packs of gray wolves can travel over 12 miles in a day to search for food. In just one feeding session, gray wolves can eat 20 pounds of food. They eat until they are completely satiated. Besides hunting they also scavenge for dead animals. In areas with people, many gray wolves subsist on livestock and garbage. Gray wolves have also preyed on humans, albeit rarely.

To prepare for fall and winter, when food isn't as readily available, gray wolves with a steady food supply store fat in various areas throughout their bodies. They are capable of numerous feedings throughout the day as the digestion process takes only a couple of hours. This allows them to ingest large quantities of meat without wasting it. Gray wolves often eat melons, berries, apples and pears during the fruits' growing seasons.