Arctic fox

The fox that is white in winter and brown in summer

The Arctic fox changes its coat twice a year: white as snow in winter, brown like rocks and grass in summer. Its fur is so warm it doesn't shiver even at −50 °C! It hears a mouse under the snow and dives in head first to catch it. When food is scarce, it follows polar bears and eats their leftovers.

The Arctic fox (Vulpes lagopus) lives on the Arctic tundra and sea ice and has the warmest fur of any mammal: it survives −70 °C and only starts shivering at −40 °C. Short ears and muzzle and furred soles (lagopus — 'hare foot') cut heat loss. Diet: lemmings (numbers follow their 4-year cycles), bird eggs, carrion; it may follow a polar bear for 1,000 km. Dens are used for centuries and have up to 100 entrances; litters reach 14 pups (a record among carnivores). As the climate warms, the red fox moves north and pushes it out. Rare in Scandinavia, but overall Arctic numbers are stable.

Fun facts

• The Arctic fox survives −70 °C — a record among mammals.
• One mother can have 14 pups — the most of any carnivore.
• Arctic fox dens are used for centuries and have 100 entrances.