As summer approaches and temperatures climb, I thought it would be fun to journey north and visit a creature that builds complex underground homes and doesn’t start shivering until temperatures get cold. Like really, really cold. Read on to discover a few facts about the arctic fox (Vulpes lagopus).

• How cold does it have to be for an arctic fox to start shivering? About −70 °C (-94 °F). The Smithsonian notes this small creature is one of “the most superbly cold-adapted mammals.” 
• Those adaptations include short ears and a small muzzle, which minimize body surface area (and, by extension, possible points of heat loss). The animal even has fur on its paws to help it walk on ice.
  
• Foxes also stay warm thanks to their amazing multilayered coat. Scientists sometimes refer to this as “pelage” (derived from the Latin word for hair, pilus). This coat changes colors season-to-season – vacillating between grayish-brown in the summer and a striking white in the winter. Other populations have coats that are a beautiful shade of steel-bluish grey.
• Arctic foxes feed on other small critters like lemmings, voles, rodents, eggs, fish, and decaying animals.
• Their homes are generally situated in frost-free areas, often built into low mounds, or ridges of stratified sand and gravel. Dens can be massive, with dozens of entrances giving way to a complex system of underground tunnels, which can cover up to 1000 square meters. 
• According to NOAA, some arctic fox dens have been used for centuries by generations of foxes. 

(Image Credit (clockwise from top): Creative Commons: braerik, Wikimedia Commons, Creative Commons, Mark Dumont, Cloudtail the Snow Leopard / Source: Smithsonian Museum of Natural History: North American Mammals, Wikimedia Commons, NOAA: Arctic Report Card: Update for 2012, Arctic Fox)