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One Picture

One Picture


Photographer: Joel Sartore
Subject: Hibernating Arctic
ground squirrels
Where: University of Alaska-Fairbanks
Camera: Nikon D3 with 24-70mm lens
Exposure: ISO 250, 1/15th second at F14


Sleeping Beauties

Should astronauts ever venture to Mars or beyond—perhaps with a friendlier onboard computer than HAL of the classic sci-fi film 2001: A Space Odyssey—they may have to pass the years en route in a state similar to hibernation. And the success of their mission could depend in part on what scientists learn about a chunky rodent known as the Arctic ground squirrel. Here are two of them, male and female, that were profoundly asleep while Joel Sartore made their portrait in February. The scene was a snowy parking lot at the Institute of Arctic Biology on the University of Alaska-Fairbanks campus, where research into the extraordinary means by which these abundant mammals survive the tundra’s glacial winter is of special interest to NASA.

There are 21 ground squirrel species of the genus Spermophilus in North America, and most of them are scattered over central and western states and provinces. Smallest of the lot is the spotted ground squirrel, found in the arid Southwest. Just eight inches long, it weighs barely six ounces. The Arctic ground squirrel is a giant by comparison. A mature specimen might measure 20 inches from nose to tail and tip the scales at two pounds. The Inuit people named the animal sik sik after its incessant calls. Adolph Murie, the great biologist whose pioneering fieldwork led to the creation of Alaska’s Denali National Park, called it the “staff of life” for such top predators as gyrfalcons, golden eagles, foxes, and grizzly bears.

Arctic ground squirrels range from Siberia to Hudson Bay, and their colonies are found from treeline meadows to the coastal plain. What’s important is well-drained sandy or gravelly soil that enables easy digging of labyrinthine burrows. And the tundra’s rock-hard permafrost must lie at least a meter below the surface. Deep in these multilevel complexes are dens where the squirrels spend seven or eight months curled into a tight ball in a nest of caribou hair, lichens, and grasses. When the den’s temperature drops below freezing, so, too, does the squirrel’s body temperature. Yet the water in the animal’s body remains fluid even though it contains no antifreeze. Every two or three weeks the squirrel will shiver and shake for several hours—while sound asleep—to briefly warm itself to a normal 98 degrees.

Researchers, who have never recorded a body temperature this low in another animal, call the process “supercooling.” They say that mimicking this talent could conceivably allow humans to escape earth for long-distance space travel. Just don’t teach the onboard computer to sing “Daisy Bell.”—Les Line
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