They extend from 6 to 12 feet underground. Enlarged ground squirrel burrows with several entrances are often used as dens. Mating occurs in early March and early April. Gestation lasts 52 days. Litters average seven pups but may contain as many as 15 pups.
Arctic foxes are monogamous in the wild.
Both parents aid in bringing food to the den and in rearing the pups. Pups begin to emerge from the den when about 3 weeks old and begin to hunt and range away from the den at about 3 months. Family units gradually break up during September and October. During midwinter, foxes lead a mostly solitary existence except when congregating at the carcasses of marine mammals, caribou, or reindeer. Arctic foxes attain sexual maturity at 9 to 10 months, but many die in their first year.