Farley cannot figure out what the wolves are eating. While there are some caribou in the arctic tundra, they seem to pass through without the wolves disturbing them. At the same time, the wolves seem to be well-fed. Farley wonders what they are eating and why they are not starving. As he wrestles with what could possibly be their food source, he becomes aware of an invasion of different species of mice. Many small rodents invade Mike’s cabin and the area around it. Farley wakes to find that a field mouse has given birth to a dozen babies in the pillow of his sleeping bag.

On one occasion, he observes Angeline leave the den and begin to dance. She leaps onto the ground and puts her head down. After watching this behavior a half dozen times, Farley realizes that Angeline is catching and eating mice. She eats 23 mice in an hour, enough to feed herself and regurgitate food for the pups. Farley surmises that the wolves in the Barrens survive by eating mice.