The Great White Bear

by Kieran Mulvaney

  Close examination of seasonal bear movements in the Beaufort Sea helps explain the difference. Here, the periods when polar bears cover the greatest area are June to July and November to December—the times when ice is melting during the spring and re-forming during the fall. During spring, previously reliable leads widen and ultimately disappear, and during fall, many have yet to truly form. The ice is patchy and unpredictable, and fertile hunting ground has yet to reveal itself; accordingly, bears must travel far and wide in search of seals. Stronger currents in the more wide-open spaces of the Beaufort and Chukchi seas and Baffin Bay help explain the greater volatility of ice conditions and the likely need for bears to not only range more widely but also adapt on the fly to ever-changing ice conditions.

  Such volatility does, however, have its advantages. As the ice moves and grinds, it creates openings that allow more sunlight to pass through into the water below, helping fuel the growth of the plant and animal organisms that form the basis of the marine food web. Not only does that help nurture an ecosystem in which seals may be relatively abundant, but the fractures in the ice allow easier access to air for those seals to breathe.

  Conversely, in Viscount Melville Sound in the Canadian Arctic Archipelago, polar bears in general showed less movement on a yearly basis, presumably because most seals in that area are concentrated along tidal cracks and pressure ridges that parallel the coastlines of the area's islands. The ice here is thicker and more stable, with a greater percentage of solid multiyear ice, and the seals' whereabouts are more predictable—but, largely because of that solid ice cover, their abundance is reduced and foraging conditions are relatively poor.

  The fundamental centrality of sea ice to the polar bear's existence is underlined by tracking radio-collared bears and layering their movements on that of the ice over the course of a typical year. Between May and August, as the ice of the southern Beaufort Sea is degrading, bears in that subpopulation not only expand their activity areas, but they move north, where the ice pack remains robust; their movements are extensive and rapid, as they seek out feeding opportunities. In October, as the first pack starts to form over shallow water near shore, they swiftly head south and disperse east and west along the coasts as the ice solidifies over the course of winter.

  As the bears move, so does the ice beneath their feet. In the Beaufort Sea, it travels in an immense gyre, carried by the currents south along the west coast of Banks Island, west along the Canadian and Alaskan coasts to a point just past Point Barrow, after which it heads north once more. And yet, despite this constant movement, despite the lack of what, to us, would be obvious visual cues in a landscape composed of solid pack stretching to the horizon, polar bears are able to compensate. Ian Stirling notes that he has often recaptured polar bears in the Beaufort Sea, "far from sight of the nearest land, within a few kilometers of where they were first caught two, three, or even more than ten years earlier."

  Arguably even more impressive are those bears that den on the pack ice; for several months, as the cubs suckle from their mother in the dark warmth of their den, currents transport them hundreds of miles from their original point. No other vertebrate is transported passively and blindly as far and wide as are denning polar bears. And yet, somehow, even though when they emerge it is in a place where they have never been and where they did not choose to travel, they are able to find their way back to the area from which they came, and which the mother had already established as her home range.

  Exactly how polar bears orientate and navigate in this way is unknown. Perhaps a clue lies in the discovery by researchers Malcolm Ramsay and Dennis Andriashek of the route taken by female polar bears with cubs as they left their maternity denning area south of Churchill in February and March and headed back onto the ice. The shortest route would have been due east. Instead, they took straight courses that paralleled each other, the mean course of which was 39 degrees True (a little north of northeast). That might suggest that, like migrating birds or, it is believed, whales and dolphins, polar bears take advantage of cues in the Earth's magnetic field, that they possess a kind of mental compass that leads them, instinctively and unerringly, to where they need to go and where they have been before.

  Polar bears are at once solitary and social. They are solitary in the sense that they do not, outside of mothers with cubs, live in any kind of organized familial or hierarchical structure. They do not live in pods, as do whales, or in packs like wolves, or in prides like lions. And yet, in some ways, they are as social as—or even more so than—all of those.

  Like tigers and leopards, polar bears hunt alone, make no lasting connections with their mates—do not, in fact, see them after copulation has been completed—and, in the case of males, have nothing to do with their offspring. And yet, largely because of the particular circumstances of their environment and its challenges, they frequently come together in what can only be described as social settings and display what can only be considered social behavior.

  As Richard C. Davids has observed, "Polar bears used to be considered lonely nomads, among the most solitary creatures in existence. I wondered about that on my first trip north, when I saw five big males lying in the kelp along shore, their noses all but touching."

  Early during his research on Wrangel and Herald islands in the Russian Arctic, Nikita Ovsyanikov noticed a variety of social interactions that caused him to ask whether the polar bear is "a solitary ice wanderer or a more social animal?" The answer, he found, was more complex than prevailing theories of the bears' purely solitary nature initially supposed.

  Ovsyanikov was especially well positioned to make those observations. The hostile, uncertain nature of the Arctic environment means that, for all that polar bears mark out their own clearly defined home ranges, bears—like all animals—must go where the food is. Perfect hunting conditions, high prey concentrations, or a sudden absence or abundance of sea ice may all lead on occasion to a polar bear agglomeration. Given that the fickle nature of sea ice makes defending territory a proposition of dubious value, and the considerable size and strength of other polar bears make it one of particular danger, a certain acceptance of others would therefore be explicable. Indeed, Ovsyanikov at times counted as many as 140 bears gathered in close proximity at his observation area at Cape Blossom on Wrangel Island. As Geoff York explained it to me, "It isn't that polar bears are asocial. It's that they have no particular reason to be social most of the year. When it suits them, they are quite gregarious."

  There were occasions during Ovsyanikov's research when bears showed suspicion of, and even hostility toward, each other, mostly when females with cubs resisted approaches toward their kills by adult and subadult males. There were, however, numerous other instances when bears shared food willingly.

  "In fact," Ovsyanikov wrote, "when eating from the same carcass, the polar bears I observed were often more tolerant of each other than highly social wolf packs are around a kill. I soon realized there was more to it than simple tolerance."

  Ovsyanikov noticed that bears seemed to take turns in feasting on, even "possessing," the carcass, but that when others approached, perhaps circling around the carcass, gently initiating nose-to-nose contact, then, once they had finished their meal, the original bears willingly gave up their place at the table.

  It is not atypical for a bear that has killed a seal to allow, after some growling and lunging, a rival to partake in its kill. But the extra degree of sharing documented by Ovsyanikov might be at least partly explained by the fact that the bears he was observing were feasting not on ringed or bearded seals, but on walruses.

  As we have already seen, hunting walruses is an altogether different proposition for polar bears than stalking or waiting for seals. More than two thousand pounds of meat and blubber wrapped in thick hide and punctuated by two curling tusks, walruses are fearsome opponents. A desperately hungry bear may leap on the back of a walrus, biting its shoulders and neck and attempting to bring it down, but the would-be prey often s
ucceeds in dragging its putative predator into the sea, where the pursuit will end; although polar bears are marine mammals, in the water they are by far no match for the more completely aquatic pinnipeds. From Ovsyanikov's observations, "only a few experienced animals were able to make a kill, and the walruses killed were all calves."

  Notwithstanding their size and strength, walruses seek safety and security in numbers, frequently gathering in large herds along the water's edge or squeezing tightly onto ice floes. Although an individual mature walrus is more than a physical match for its ursine counterpart, a polar bear charge toward a gathering of walruses will almost invariably induce headlong flight into the water, a surging mass of elephantine blubber churning up a frothing foam of frigid ocean and providing openings of which an alert bear will seek to take advantage.

  Ovsyanikov describes one instance in which a female on Wrangel Island "jumped down the small cliff and ran quickly along the front of the rookery, creating panic among the animals, all the while scanning the mass as if searching for something. Suddenly she rushed toward one group of fleeing walruses, mixed in with the rearguard for a moment, and snatched out a small calf."

  The bear was just beginning to tear the skin off the calf's head when a large mature male bear appeared and, after brief resistance from the female, stole her bounty from her. So the female, clearly an adept hunter, repeated what she had done before, rushing the walruses until they stampeded for the sanctuary of the sea. "In the ensuing panic," wrote Ovsyanikov, "she made a short rush to the left and seized another small calf. It all happened so quickly that no walrus even tried to defend it."

  There are no recorded examples of polar bears cooperating to hunt walruses—no reason, in fact, to believe that mature polar bears ever work together with intent at all. Ovsyanikov, however, has suggested that the attempts of bears to hunt adult walruses and the fact that those attempts almost all initially end in failure ultimately add up to the greater ursine good. "It is quite possible," he writes, "that a walrus that is repeatedly attacked and wounded is well on its way to an early demise, thus increasing the polar bears' chances of getting a meal."

  When such a meal does come, Ovsyanikov suggests that the shared eating behavior that he observed on Wrangel serves a practical function, that of "opening up" the tough carcass and making it easier for all participating bears, including the one that killed the walrus in the first place, to gain their fill. But the social element of polar bear lives extends beyond the purely pragmatic.

  While there is no recognized social structure among polar bears, there is an identifiable and noticeable pecking order, with mature males inevitably at the top, and subadults at the bottom, below even cubs with their mothers. At feeding sites, the arrival of a large male produces a noticeable stir among other bears, while subadults approach warily and cubs feeding alongside their mothers are sufficiently emboldened to make brief charges to keep them away.

  And despite their largely solitary nature, individual bears will for a while pair up with others from their particular rung of the social ladder. They may rest together, sleeping close to each other on day beds they have fashioned for themselves out of snow as they wait for the sea ice to re-form. Polar bear mothers with cubs may spend time in each other's company. Subadult and even mature males walk together and play together, engaging in mock battles with each other, ritualized play fighting that may be quite rough and may last for forty-five minutes at a stretch, but in which harm is rarely done and injuries are almost never inflicted. Because of their awareness of their own power and that of their peers, polar bears take care to avoid full-blooded conflict with each other whenever possible, with one exception: when the time comes to mate.

  ***

  The two bears have survived their subadult years and grown into fully mature males. In the process they have gone their separate ways and may never see each other again. But now, at five years old, they have more immediate and pressing concerns.

  It is March; winter is drawing to a close, spring is around the corner, and the sea ice will soon begin to melt. In the snow that covers the floes, bear tracks reveal an extra purposefulness. The bears that have made them have not paused to sniff the air or meandered toward cracks in the ice; they have stridden forward, plodding relentlessly for sixty miles or more. These are the tracks of fully grown males who, across miles upon miles of fiat, frozen wilderness, have caught the scent of a potential mate, apparently secreted through glands in the sole of a female's paw, and are driven to find her. When they do, they find other males in her presence, each with the same goal.

  And so the battle begins.

  Mating battles between mature males are rarely observed, but their ferocity can be inferred. For one thing, male polar bears are significantly more massive than females, an example of a phenomenon known to biologists as sexual dimorphism, in which males and females are dramatically different in size, appearance, or coloration. Almost invariably, when males are substantially larger than females, they are also significantly more numerous and must therefore compete with each other for the attention of a possible mate. There are reckoned to be, if anything, slightly more female polar bears than males, making the species the exception to the rule; but the long period over which females raise cubs means that during any given mating period, only approximately one-third of the mature females are available to breed. Competition, therefore, is intense, and further evidence of the severity of the fights that take place can be found in older males, which have far more scars and broken teeth than do females of the same age. Geoff York has told me that "I have seen two males, absolutely battered, exhausted, and emaciated, following a female to breed. The male in the rear of the group had one ear hanging to the side of his head and numerous slash and puncture wounds. A massive slash to the groin was large and deep enough to insert your full hand, yet this bear continued its pursuit." As he wryly observes, such behavior is why it is assumed males live shorter lives than females.

  When one male has seen off his rivals and emerged victorious, he escorts the female away from the more heavily trafficked areas of prime seal habitat where the greatest number of bears is likely to be found, nudging and leading her to more secluded or remote spots, either high on a mountainside or far out on the pack ice. And then they begin to mate.

  The couple spends several days together, during which they mate repeatedly. They copulate several times before the female releases an egg, and several more after that before the egg is successfully fertilized, a strategy that ensures the egg is not released without a mate being available and that it is not wasted on a mate that is unsuitable.

  The female may mate with more than one male, and when she gives birth, each of her two or three cubs may be sired by different fathers. Whether she breeds with one or more, the end result is always the same. The two go their separate ways and likely will not see each other again.

  The male wanders off, perhaps in search of another mate. In time the female will begin probing snowdrifts, looking for a suitable spot to make a den and give birth. But it will be a few months before she is ready to take that step. For now, she must eat.

  Encounters

  In the distance, near the horizon, there is movement. From where he stands, on the edge of the fast ice, the bear cannot quite make out the nature of the creature that is moving, or whether it has seen him. He raises his nose to the air, catches the scents that blow on the breeze: faint, and faintly familiar.

  It is not a smell to which he is altogether accustomed, not the easily identifiable odor of a walrus on an ice floe or a ringed seal lying in its lair. But it is not entirely new to him. He has smelled it before, sometimes stronger, sometimes intermingled with a variety of fantastic and otherworldly sensory delights; in times past, on his way to the shores of the bay, waiting for the ice to freeze, he had dared to explore their provenance. He had been younger then, and hungrier, braver perhaps, more desperate certainly.

  He had ventured forth in search of food, had been able to procure s
ome scraps here and there, had even managed to avoid being seen in the process. Even so, as he became older and wiser, more accomplished at finding food where he was supposed to, where his mother had taught him and his brother so long ago, the need and temptation to take such risks disappeared.

  He placed his front paws on a hummock to gain better elevation, but the scent was already starting to diminish. The creature was moving away. For a moment, the bear's predatory instincts urged him to follow, to stay upwind and to close the distance until he could make a decision on whether to attack. But it was an urge he could easily enough resist. The ice was fractured here, there were many leads, and seals were plentiful. There was no need to invest precious time and energy in stalking that potential prey. Besides, the effort might prove not only fruitless but potentially dangerous. Even on those occasions in the past when he had managed to snatch food scraps from the midst of such creatures, he had felt an uneasiness, a sense of danger always lurking.

  Far better to turn back out to the pack ice. Let the creature take its scent off the fast ice and back onto land, unmolested.

  That ours became the dominant species on Earth owes much to a series of circumstances, some confluent, some leading to others, some the product of good fortune, others of evolutionary adaptation: intelligence, a social nature, bipedal motion, an omnivorous diet, opposable thumbs, the use of fire and tools, an ability to adapt to a variety of climates and survive catastrophic events that limited or eliminated competitors and predators—ultimately, of course, our ancestors' development of agriculture and the knowledge to alter the environment to suit our tastes rather than being obliged to adapt to its whims.