Sunday, January 15, 2012

The Wanderer: The Arctic Fox by Garry Hamilton

New studies suggest that the secret to winter survival for some Arctic foxes is their incredible ability to keep on the go for months on end. 

IN SPRING 2008, Canadian biologists began monitoring a female Arctic fox living on Bylot Island, a landmass of mostly mountains and glaciers that rises from the Arctic Ocean just north of Baffin Island, some 250 miles west of Greenland. At first, there was nothing unusual about the animal’s behavior. She found a den and a mate, and together the pair carried out the exhausting task of rearing 11 hungry pups. But as fall set in, a switch seemed to flip inside her brain—a switch that caused her to do something that for most other animals her size would be a death sentence: She began to wander.

Initially, the fox moved northward off the island and onto the permanent Arctic ice cap. She remained there for nearly four months, zigzagging hundreds of miles over crumbled ice under conditions that included minus 40-degree F temperatures and close to 90 days without direct sunlight. Come April, she headed southwest, eventually reaching Baffin Island, where she spent three weeks tracing a 620-mile loop before returning for yet more time on the sea ice. She wasn’t finished. In mid-May, she turned west and trekked another 750 miles before eventually spending the summer of 2009 on Somerset Island, a low-lying mass of mostly barren rock the size of Vermont. By the time a year had passed, the intrepid canine had logged more than 3,100 miles.

Unlike many denizens of the Far North, Arctic foxes don’t hibernate, hunker down in a den beneath the snow or migrate south during the cold months. Instead, they remain active, taking the full cruelty of the Arctic winter head on. How they pull off such a feat has long been a mystery, but recent advances in satellite-tracking technology have finally enabled scientists to monitor the animals’ movements during the nine months of the year when the little predators are otherwise inaccessible.

The first completed studies suggest that, at least for some of the creatures, one secret to survival is their incredible ability to wander. Arctic foxes that decide not to stay in one area during the long winter appear to be true nomads, roaming distances that are continental in scale. “What we’re finding is that for most of the year, the foxes that leave don’t seem to have a home range,” says Dominique Berteaux, a biologist at the University of Quebec at Rimouski who heads the ongoing research on Bylot Island. “There’s no home. It’s all range.”

Records of the species’ unusual behavior date back more than a century. During his failed attempt to reach the North Pole on foot in the spring of 1895, Norwegian explorer Fridtjof Nansen encountered several sets of fox footprints as he crossed the ice cap above the 85th parallel. “What in the world was that fox doing up here?” he wrote in his journal. Nansen, who was heading home at that point, took this sign of life to mean land was near. In fact, he had another three weeks of solid slogging before he reached the remote islands now known as Franz Josef Land.

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