The Shadow Knows

In Alaska's Far North, the arctic fox shares its secrets of survival

12-01-2001 // Tom Walker
The Shadow Knows magazine layout - arctic fox and polar bear

SOMETIME DURING the fading 16-hour-long night, the polar wind ebbed and the ground blizzard subsided. In dawn twilight and "warm" minus-20-degree F temperatures, my Inupiaq companions began to load their sleds for a foray onto Beaufort Sea ice along the northern coast of Alaska to hunt seals. Nunsingaya, the elder, said that he believed the high wind had opened leads in the ice not far from shore. With luck this day, we would find one swarming with seals.

I had joined these Native subsistence hunters to learn how they pursue such highly prized quarry on the trackless ice, and perhaps to take photographs of polar bears or other wildlife. About a mile from shore, we crossed a skein of arctic fox tracks zigzagging across the ice. We paralleled them for about a mile when, suddenly, the tracks veered sharply to the north. Nunsingaya stopped to examine them. He spoke two words in Inupiaq and abruptly we changed direction to follow the tracks into the cutting head wind. A short time later another set of fox tracks angled in and joined the first. The elder mumbled and shook his head. A half mile farther on, yet another set of tracks converged on the two. Off in the distance, a thin fog wafted above the ice.

Cautiously we stalked forward to a pressure ridge at the edge of the fog. Nunsingaya went ahead and peered over. Shortly he beckoned us to join him. An open lead stretched westward. Black dots situated along it were hauled-out seals.

Directly in front of us, four foxes jousted over scraps in a smear of red-stained snow. Now I understood why we had veered from our chosen path: The foxes had scented a polar bear kill and in turn led us to open water. Nunsingaya turned to me and whispered, "Polar bear catch seal, feeds its shadows, now maybe shadows help feed us."

If I learned anything that day, it was an awareness of small things. I never would have thought that a change in the direction of those tiny fox prints would mean so much. It turned out to be just one of several lessons my companions taught me about one of the Far North's most compelling creatures.

Arctic foxes, nomads of the circumpolar, high-arctic biome, lead a solitary life except when congregating near a rich food source, such as a polar bear's leavings. These foxes range farther north than any other terrestrial mammals in the world. (Polar bears are classified as marine mammals.) Explorers once reported seeing a fox within 87 miles of true north and another within about 52 miles of the northern pole of inaccessibility (the point in the arctic ice pack that is farthest away from land).

To live in such bitter conditions--killing cold, stabbing winds and months of polar darkness--these six- to ten-pound predators evolved the densest winter pelage of any land mammal, perhaps rivaled only by that of the river otter. Their underfur can be two and a half inches thick and their guard hairs five or more inches long. Short ears, legs and snouts radiate little body heat. Densely furred paws insulate pads from the cold and provide traction on ice.

For camouflage, arctic foxes change color by season. White winter pelage matures in September and October, with the changeover complete by November. The winter fur then molts in early April and by June transforms to brown and tan. These color shifts, scientists believe, may be triggered by seasonal changes in daylight and ambient temperatures. Some arctic foxes in the southern portion of their Bering Sea range are called "blue foxes" because of their year-round charcoal coloring.

In early March and April, two months before the end of winter, foxes pair up and breed after a playful courtship. As spring days lengthen, the pair returns together to a traditional den site. Such sites may be used more than once by the same pair, or passed from one generation to the next. They also may be claimed by other wandering pairs. Researchers found one den site that they estimated to be 300 years old, with as many as 100 entrances.

After a less-than-two-month pregnancy, the female gives birth. Litters vary from 6 to 15, but Russian scientists once documented a litter of 22. Pups emerge from the den when about three weeks old and are fully weaned by six weeks. At three months, they begin to range away from the den to hunt on their own. The family breaks up in September or October.

Compared with most other canids, the male arctic fox is an attentive and adept provider during the denning period. At first, the male does most of the hunting for the family and even challenges bears and wolves that venture near the den. When her pups are about two weeks old and begin to eat solid food, the female joins the hunt but stays closer to the den.

 

The Shadow Knows magazine layout 
Photo: © TOM WALKER

SEASONAL WEAR: Dressed in her warm-weather coat, a female fox is still undergoing her seasonal molt from winter white to summer brown. "She looked like a small dog with a very bad poodle cut," says the author, who has visited the refuge regularly for the past two decades to photograph wildlife.


 
Keen predators, arctic foxes possess acute senses, speed--they can run as fast as 25 mph--and remarkable adaptability. I once watched a fox locate lemmings at a considerable distance by sound alone. Each time the fox would make a quick stalk, then stand motionless, its head twisting side to side as it marked the movement of the rodent beneath the snow. After a pounce with stiff forelegs that broke the hard crust, the animal captured its prey.

Although these canids eke out a living where other species would starve--shadowing bears for scraps, feasting on carrion and taking bird eggs--their reproductive success ultimately is tied to lemming cycles. When lemming populations are low, some foxes starve and production of offspring falters. At the height of the lemming cycle--about every four to five years--fox litter sizes increase and survival rates soar. For an average litter of 11 whelps, adult foxes must provide 30 lemmings per day. The demand increases to more than 100 per day just before the pups abandon the den. During the denning period, which lasts roughly 12 to 14 weeks, the adults capture about 3,500 to 4,000 lemmings.

Determining a fox's home range is problematic because of prey fluctuation and habitat variation. Some foxes appear to be itinerant and move great distances over the polar ice. Alaska researcher Bob Burgess marked 174 foxes in 1992 and 1993 at Prudhoe Bay. Many wandered; others stayed close to the oil fields. However, one collared fox was captured near Aberdeen Lake in Canada's Northwest Territories in February 2000--a straight-line distance of 1,200 miles.

In another study, biologists Erich Follmann and Phillip Martin collared ten foxes at Prudhoe Bay to track movements. They were surprised to learn that the animals never left the area, partly because of the availability of human foods. They had become beggars and dump diners. Their home ranges at Prudhoe measured 27 to 29 square miles, compared to 38 to 118 square miles for foxes that live away from the oil fields. And the Prudhoe arctic foxes' numbers grew faster and larger than in other areas. To date, researchers have not found a direct link between such artificially inflated fox populations and the decline of threatened birds that range in the Prudhoe Bay area, such as the spectacled eider. But, says one Alaska scientist, "the impact of oil field development is more subtle than you would think."

While watching arctic foxes at their den sites, I'm always amazed at their hunting skills. Once, during an early July trip to the Arctic National Wildlife Refuge, I situated myself on a bluff above Camden Bay. There, I watched an adult male fox venture forth from his den in late afternoon and return almost hourly with mouthfuls of lemmings and other prey.

Despite the time of year, two blizzards already had swept by and the polar northeasterly wind carried a constant bite as I hunkered down near the edge of the arctic ice. The pups first emerged on a relatively warm summer day and were initially shy. A shadow would send them tumbling back into the den, which I suspected was once the labyrinth of some arctic ground squirrels. Each day, the young foxes' excursions grew longer in duration.

 

The Shadow Knows magazine layout 
Photo: © TOM WALKER

FAMILY TIES: Unlike most other canids, a male arctic fox is attentive to his offspring during the denning period, which can last 12 weeks or more. Providing food for the family is no easy task, however. Youngsters such as these pups, emerging from their den beneath some driftwood, require huge amounts of prey before the group breaks up in early fall.

 

I had found this den five years before and expected it to be in use. On the refuge coast, den sites are somewhat limited by permafrost; they tend to be located under driftwood piles, in the tops or sides of eskers and pingos or along riverbanks, which usually become snow free earlier than surrounding terrain.

The two adults at the Camden Bay site looked markedly different. Except for a few long guard hairs, the male wore his short, summer coat but the female wore half winter coat and half summer coat. Her tiny, slender back was half jutted out from densely furred winter forequarters. She looked like a small dog with a very bad poodle cut. She rarely ventured from the den and then only to rest at the main opening. Both adults ignored me, the male sometimes passing quite close as he wandered by on his hunting trips.

I counted a total of seven pups, but within a short time only five of the youngsters gamboled around the den. Within two weeks of their emergence, one pup--indistinguishable from its siblings in size or color--varied markedly in its behavior. While the other pups seemed tentative when just a few feet from the den, this pup was an inquisitive wanderer. One afternoon it trailed the male out across the tundra--seemingly ignoring barking commands to go back--until both disappeared behind a distant esker to the south. About an hour later, the male returned with a mouthful of lemmings and disappeared down the main entrance. I searched the open tundra with binoculars but the pup was nowhere in sight.

After a short while, the male emerged from the den and trotted off to the north. Several hours later, I saw movement on the tundra to the south. The pup! Before long it crept weary and bedraggled into the safety of the den. I could only wonder at its adventures and marvel at its luck in avoiding golden eagles and other predators.

Did the pup's marked boldness signify a higher likelihood of survival or was it a sign of added vulnerability? I knew that most of the litter would die in early winter due to predation, starvation or possibly premature den abandonment. But perhaps an inquisitive, intrepid pup would be more likely to find food in this rugged environment than its shyer siblings.

Late the next day, bush pilot Don Ross landed to pick me up. Just as I loaded the last bag onto the plane, the wickering call of the adult male fox drifted over the tundra. Moments later we were airborne and banking over the Beaufort Sea. Off in the distance, dense ice floes stretched to the pole. Somewhere amid the ridges and icebergs, a polar bear stalked seals and I wondered if the bold pup would one day be its shadow.

Alaska photojournalist Tom Walker wrote about caribou in the Arctic National Wildlife Refuge in the August/September 2001 issue.

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