The Great White Bear (12 page)

Slowly, surely, the bear closes in on its target. Then, suddenly, it charges.

Polar bears are not built for sustained speed; their heft and insulation work against them and they soon begin to overheat. But over distances of forty or fifty feet, they are capable of shockingly explosive bursts, and the moment they close to within that distance of their target, they take off, pounding forward with no further pretense of subtlety or subterfuge. One can only imagine the overwhelming shock and panic that must crash like a tsunami over the seal as this monstrous beast appears as if from nowhere, casting aside its cloak of invisibility and roaring toward it with frightening resolve and force.

Desperately, the seal flops toward the nearby breathing hole through which it emerged onto the ice, and its frantic bid to seek the sanctuary of the water that must suddenly seem so far away is an illustration of why ringed seals predominantly haul out of the ice by themselves and not in groups of several: a mass of blubbery bodies flopping pell-mell for safety would obstruct one another's passage so that each and every one of them would be at the bear's mercy.

(Indeed, notes University of Alaska ringed seal expert Brendan Kelly, those occasions when numerous seals do haul out by one hole frequently have entirely predictable outcomes. "When such groups are alarmed, they all try to escape down the hole at once," he says. "Most often that results in two or three seals with their heads submerged but their bodies unable to squeeze in at the same time. It is almost comical to see their hind flippers flapping madly in the air.")

As it is, by the time the seal reacts to the thundering onslaught, it is too late. The bear's jaws clamp shut around its head, then again, then again, before the predator hauls the carcass away.

A stalking polar bear does not always approach across the surface of a floe. On occasion, after staring at the intended victim as if to memorize the route, a bear will quietly slip into the water and swim through breaks in the ice, surfacing to breathe so stealthily, writes Ian Stirling, "that only the tip of the nose breaks the water between dives as the bear moves closer to the seal." Finally, Stirling continues, "it gets to the last available breathing hole before reaching the seal and slips out of sight again. After an eternity of suspense-filled seconds, the water in front of the seal explodes as the bear suddenly claws its way onto the ice after its prey."

While that may be the most spectacular mode of attack, it is not necessarily the most effective. More often than not, Stirling notes, the seal manages to evade the bear's claws and slip into the water, sometimes just inches ahead of the pursuing predator. More successful is a variation on the theme, in which bears approach their prey by means of the water-filled channels that form on top of melting sea ice in the summer, slithering along almost completely out of sight until close enough to strike.

One bear that used that particular technique showed such intelligence and awareness that even Stirling, who has studied polar bears in the wild for more than thirty years, was taken aback. After spotting a seal lying on the ice, he records, the bear stopped in its tracks and stared intently, without moving, for several minutes at a series of channels in the ice that led toward its potential prey. Then it quietly slipped into one of them and paddled gently ahead. So far, so unexceptional; what stunned Stirling was what happened when the bear came to a fork in the channel. Initially, the bear turned right at the fork; but after proceeding "about a body length," it stopped and, without lifting its head, backed up and then took the left channel, which was the one that led to the seal.

"I was amazed," Stirling wrote. "I have seen several bears lift their heads slightly to check their bearings but I have never seen such a demonstration of conscious memory."

Polar bears are more likely to use stalking as their means of predation in summer, when the ice is melting and narrow leads have widened to gaping channels, when the seals that haul out to rest do so in the open air. In fall and winter, those same seals take advantage of the breathing holes that they maintain in the ice, which are nominally hidden and protected by the seemingly anonymous snowdrifts that form over them. But a ringed seal's sanctuary is one that a polar bear's powerful sense of smell can pinpoint literally from miles away.

A polar bear zeroes in on a seal sheltering within its lair in the same way it does on one that is basking in plain view: its apparently aimless wandering comes to an abrupt halt, its nose sniffs the air. The bear may clamber onto a pressure ridge to gain a better sweep of the area, may move its head from side to side as if triangulating the scent and confirming the direction. Then it sets off toward the hidden bounty until, as it closes in on the lair in question, it suddenly speeds up and then, at the last moment, rears up on its hind legs and drives its forepaws down with a crash through the roof.

"A lair might be a meter, could be five meters long, and might have multiple chambers, but somehow, from that point on a pressure ridge, a bear is able to figure out not only which snowdrift to go for but also at which point in a snowdrift to make a hit," marvels Brendan Kelly.

If the bear is lucky, its attack crashes the roof onto the breathing hole itself, blocking the exit and trapping any seal that had been lying in the snow cave. Sometimes, however, the seal slides through the hole and into the water in advance of the bear's final lunge, or had already recently vacated its rest area.

When that happens, the bear will wait.

At times a bear must wait very patiently indeed, for perhaps an hour or even more. Most of the time, it will lie quietly on its stomach and chest, its chin close to the breathing hole or ice edge. It must remain not only still but completely silent: even the slightest movement on the ice is magnified as it reverberates into the water below. Such is the patience that some of the first explorers and naturalists to observe the behavior assumed that the bears were sleeping on the ice.

Bears do not, contrary to popular myth, cover their black noses with their paws to make themselves completely white. An extension of that story posits that it is always the right paw that covers the nose, and that all bears are left-handed—a wrinkle that also, from hours of observation of bears swiping seals with either forelimb, appears to be inaccurate.

Another tale, yet to be disproved, is that bears will, at least on occasion, be inventive: that they will, for example, build walls of snow behind which to hide as they wait at a breathing hole, or even that they will push blocks of ice ahead of them as they creep forward during a stalk. Although both prompt the raising of an eyebrow, the latter seems especially improbable; seals are as attuned to the aural as to the visual, and the sound of ice scraping against ice would be far more likely to carry into the water and the ears of an attentive seal than the gentle padding of a predator's paws. (It is more likely that bears may push snow ahead of them with their noses as they crawl; polar explorer Eric Larsen recalls that a bear that apparently was stalking him on the ice of the Arctic Ocean in 2005 was doing just that.)

There is, however, some circumstantial evidence for another claim, that bears will sometimes use tools—specifically rocks or blocks of ice—to break through the most resistant of snow caves. Bears in captivity have certainly been observed to throw pieces of ice, and Erik W. Born relates this tale from Inuit hunter Kristian Eipe, who encountered the body of a recently killed walrus: "Before the bear had sat down to wait for a walrus to come up for air, it had fetched a lump of sea ice from the tidal zone," Eipe asserted. "It had prepared the lump of ice so that it was completely smooth, thereby making a tool which it could use to smash the walrus on the head ... The bear's claws had made deep marks in the fresh ice. It had attacked and hit the walrus on the head with its weapon ... The bear had crushed its skull from the muzzle to the back of the head, the skin there was torn to pieces, such was the force of the blow." In 1972, H. P. L. Kiliaan of the Canadian Wildlife Service was sledding across Sverdrup Inlet on Devon Island with two Inuit when one remarked he had seen a place where a bear had used a block of ice to smash a ringed seal lair. The three went to investigate and, reported Kiliaan, found a lair that had been broken open, the tracks of a female bear and two cubs, and, next to the breathing hole, a chunk of freshwater ice he estimated to weigh about forty-five pounds. By following the tracks, Kiliaan deduced that the bears had broken the ice from a much larger piece and then rolled it toward the breathing hole. He wrote:
What happened next is not certain, but we may consider the following possibilities:

1. The bear used the piece of ice to smash through part of the snow roof. Once the roof was thinner it would be possible for the bear, using its own weight, to break through the rest. Then should the seal surface, the bear would be able to take it by surprise.
   
2. The bear heard the seal come to the surface and tried to smash it on the head with a piece of ice, in an attempt to stun or kill it.
   
3. The bear, after an unsuccessful attempt to catch the seal in the conventional way, broke off the piece of ice in "anger," frustration, or play, and rolled it towards the opened aglu,
   ^*
   and by sheer coincidence left it there.
   

That bears do lose their temper or vent their frustration on those occasions when they fail to make a kill—when a seal escapes a bear's lunge, effectively wasting the minutes or even hours the putative predator has devoted to securing a meal—is another tale told often and mostly apocryphally. In his book
The World of the Polar Bear,
Richard Perry cites several observers who report having seen flashes of bear temper in the wake of an escaped seal, ranging from splashing the water surface furiously, to swiping at snow and throwing it in the air, to even hitting a nearby rock outcrop and, so the unsubstantiated story goes, supposedly breaking the bones in its paw in the process.

But when a bear does succeed, when it surprises a seal and leaps in time to seize its victim in its jaws, when it is able to rip its prey away from the sanctuary of its breathing hole, it is an expression of such raw power that an observer may feel chilled by the ferocity of what he or she has just witnessed. Charles Feazel, a polar geologist who in the course of his work had many encounters with polar bears, is a case in point, as detailed in his book
White Bear:

Yesterday I watched a bear kill a seal. I shouldn't have. Like the strength sapping cold, the memory seeps inward, displacing all focus on my scientific mission. The scene was a grim lesson in arctic efficiency. Shuffling along through the snow, the big she-bear looked peaceable enough. Then scenting, through more than two feet of snow cover, a seal's breathing hole in the ice, she froze ... Suddenly, rearing up on her hind legs, she towered, motionless, a silent, menacing apparition almost eight feet tall. She waited. Then, with a dive so fast the eye couldn't follow, she plunged nose first into the snow. A great cloud of white powder exploded into the still air, mercifully obscuring the seal's final agonies. With her massive jaw and thick neck muscles, the bear crushed the seal's skull and lifted its 150-pound body clear of the water. The power of the upward jerk pulled her prey through the narrow opening in the ice, and broke most of the seal's bones. Swinging her long, snakelike neck from side to side, the bear flayed the seal ... The bloody carcass, sleek as a red torpedo, slithered across the snow, a grotesque puck in a deadly game.

A bear's principal nutritional target is not the seals' meat.
^*
The proteins in red meat are difficult to break down, particularly in an environment where liquid fresh water—essential for protein absorption—can, at least at some times of the year, be difficult to find. Instead, the bears zero in on the seals' thick layers of fat, which are rich in easily digestible calories. So focused are polar bears on seals' fat that researcher Andrew Derocher has referred to them not as carnivores, but lipovores.

(They are not alone in their lipophilia. One day on the
Arctic Sunrise,
as I stood on deck simultaneously savoring the view and detesting the cold, I described to one of the scientists on board my impression of
muktuk. Muktuk
is the name given to the skin and blubber of bowhead whales, often thinly sliced; during a visit to an Inupiat community earlier in the voyage, I had been offered some and had accepted. To coastal peoples of the Arctic,
muktuk
is a delicacy; to my admittedly vegetarian palate, it was chewy, oily, and indigestible. What I was missing, said the scientist—who had spent much time on the ice with Alaska Natives—is that when the temperature is firmly in the double digits below zero, the body craves nothing so much as fat, which is easily digestible and readily releases warming energy. In that context, the idea of whale blubber as a satisfying source of calories makes perfect sense.)

After killing a seal, a bear tears chunks away from the corpse and swallows them almost without chewing, desperate to consume as much as possible as soon as possible before the scent of the kill attracts competitors. As the meal progresses, the bear becomes more refined, almost to the point of an incongruous daintiness, using its incisors to shear away the fat from the meat and, if it has the time, peeling the apparently undesirable skin from the fat.

Polar bears are astonishingly efficient predators, not just in their ability to catch prey but also in their digestion of that prey. A 1985 study in the
Canadian Journal of Zoology
calculated that they can assimilate 97 percent of the fat they consume. The report's author, Robin Best of the University of Guelph, calculated that the average active adult polar bear would need roughly five pounds of seal fat a day to survive—a target easily reached with any seal more than a month old and comfortably surpassed with an adult bearded seal, which on average would provide enough sustenance for a solid week.

If uninterrupted, a bear may feed for an hour or more. If the kill is small or the bear is large (or especially hungry), there may be little left at the end of the meal; more often, however, there is some fat and much meat remaining. Unlike brown bears, polar bears do not cache the remains for future feeds; they may make rudimentary, instinctive scratching motions in the snow, but generally they leave the remains of the carcass on the ice, where they may swiftly be fallen upon by arctic foxes or subadult polar bears, which frequently take advantage of their elders' leftovers to sustain them as they learn to hunt.