<>The ancestors of Arctic fox lived on the Tibetan plateau three to five million years ago. Arctic fox live on tundra in all far northern latitudes, where temperatures plunge to minus sixty degrees F in Winter. Survival is all about staying warm and finding enough to eat. The ability to retain body heat requires a high body volume-to-surface ratio, so Natural Selection has favored arctic fox with a rounder, more compact body shape, than has the relatively larger and rangier red fox. The arctic fox has more body fat, smaller and thicker ears, a shortened muzzle, shortened legs, a thicker, brushier tail which aids in balance and as a wrap-around source of warmth, and fur-padded paws. The paws also feature countercurrent heat exchange between arteries and veins, as still another heat retention adaptation.

The arctic fox has the warmest coat of any arctic mammal, a fact that reduces their numbers when the price of fur rises. Arctic fox have been selectively bred for their fur, resulting in hybridized "blue" and "marble" fox, which were released in the wild on Aleutian and other Alaskan islands for harvest by enterprising trappers and hunters. Successful predation by the fox involves effective camouflage, so arctic fox coats change with the season. Winter coats grow in white in the Fall, and are shed in the Spring, revealing a summer coat which gradually goes grayish-bluish-brown. Arctic fox eyes have an almost permanent squint, which aids in seeing against the reflective glare of snow and ice.

Arctic fox are omnivorous hunters and scavengers. Along with the snowy owl, they are the major harvester of lemming populations, with their numbers closely tied to the over-abundance or shortage of these ubiquitous rodents.  When lemming populations dip, arctic fox may wander, looking for more lemmings, an activity that risks giving up territories and sheltering dens that other fox may take over in their absence. The mortality rate of wandering arctic foxes is three times that of foxes who stay within their territories.  <>Arctic foxes have very sharp hearing, and will listen for the sounds of their prey moving through earth or snow tunnels, after which they leap and pounce on the source, quickly digging out their prey. Voles, hares, ground nesting birds, ringed seal pups in the Spring, eggs, carrion, berries and seaweed are consumed as well.  <>Arctic fox will trail hunting polar bears, scavenging on the remains of the bear's kill, and occasionally falling prey to the bear itself. Arctic wolves also serve as a check on arctic fox, as gray wolves and coyotes do on red fox.  Like many predators, arctic fox will kill more prey than they can consume, caching the excess against times of low success in hunting and scavenging.

Arctic fox are monogamous, breeding in March and April, with a gestation period of about 50 days. They're similar to wolves, in that the male fox helps raise and provide for the kits, who arrive in litters of 5 to 10. Families include older, not sexually mature offspring, and in times of plenty, sometimes multiple generations. Arctic fox excavate and expand rodent dens, using multiple chambers and entrances.  Arctic fox may emit a sharp bark to warn each other and approaching predators.

While arctic fox are not endangered, their range is gradually shrinking as climate change enables the northward expansion of the larger red fox, which may eliminate arctic fox within their range. Males weigh, on average, 7 to 8 lbs, while females are about 6 and a half. Arctic fox live about 7 years in the wild. 

There are probably 200,000 arctic foxes remaining in the wild, but climate change is enabling the larger red fox to expand their range further north, endangering arctic foxes in those habitats.