They sometimes eat berries, eggs, and scavenged remains of other animals. Many foxes venture out onto the sea ice during winter to eat the remains of seals killed by polar bears. Arctic foxes may move long distances over sea ice. A fox tagged along the coast of Russia was captured near Wainwright, Alaska, a year later. In areas where lemmings and voles are the most important summer prey, numbers of foxes often rise and fall with cyclic changes of their prey.
Fewer pups are successfully reared to maturity when food is scarce.
There is evidence indicating that competition for food among young pups accounts for some of the heavy mortality in this age group. Their numbers do not seem to be greatly affected by trapping. In the past 50 years, the annual harvest of white foxes in Alaska has ranged from a high of nearly 17,000 in 1925 to a low of 500 in 1956. The average is about 4,000 pelts per year. The demand for arctic fox fur has diminished in recent years, but the sale of their pelts is important to the economy of many coastal Native villages.