Trained eye

Natural History, June, 2002 by Erin M. Espelie

At summer's end, a young arctic fox is learning to hunt on its own. Photographers John Eastcott and Yva Momatiuk first spied this pup as it crouched on a gravel bar at the mouth of Alaska's Sagavanirktok River, near the Beaufort Sea. It was regurgitating the indigestible remains of an earlier catch: the bones and beak of a small bird. Soon the juvenile performed a series of deliberate stalking and pouncing maneuvers. According to Momatiuk and Eastcott, it eventually caught and devoured five lemmings in "several crunchy gulps."

If the young fox is to survive the Arctic winter, it must gain weight rapidly. Adding to its standard diet of insects, berries, bird eggs, and occasional scraps of carrion, the pup increases its protein intake by hunting mice, voles, and lemmings. When the cold weather finally sets in, it may be as much as 50 percent heavier than it was in midsummer.

Winter's onset also means a change in coat. The fox's dark summer pelage will be replaced by snow-white thermal fur. Well adapted to the icy climate, arctic foxes have several other special traits, including hairy paws, pigment-protected eyes, and a long, wraparound tail.

As the sea freezes and food becomes scarce, the pup may turn to scavenging. Youngsters like this one have been known to follow polar bears in hopes of swiping some leftovers.