The Great White Bear (11 page)

In the 1930s, a hunter from Greenland saw a walrus take a preemptive, and fatal, strike against an unsuspecting polar bear.

"A polar bear had swum too close to an ice floe where a walrus family lay sleeping," he recounted. "But the bear was spotted and a large male walrus slid quietly into the water. It came up again shortly after behind the bear and slashed it with its tusks. They both dived and when they came up to the surface again, the walrus was gripping the bear with its front flippers whilst hacking at it with its tusks."

Although the bear escaped and reached shore, it soon collapsed and died, its skin perforated and organs gashed by the walrus tusks.

No surprise, then, that polar bears approach their sometime prey with a degree of caution that highlights their patience and underlines their wariness of the damage walruses can inflict.

One year, recalls Kelly, he and some other researchers "were on a ship, looking for walruses, counting them, studying them, doing exactly what we were doing on the
Arctic Sunrise
in 1998. There were twelve calves with twelve females all on one ice floe. We pulled up close, and we had finished counting them, and at that point the wind shifted slightly and they caught a whiff of us."

The walruses plunged into the water, the females doing what walrus mothers normally do: pushing their calves into the safety of the water first, and then following immediately behind. In the scrum, however, one mother was knocked off the floe before she had the chance to take care of her offspring, leaving her calf as the last remaining animal on the floe. Or so it seemed.

"At that very instant," continues Kelly, "from behind a pressure ridge, this bear stands up. It has clearly been there that whole time. It rises up, leaps over the pressure ridge, grabs the calf—doesn't kill it, picks it up like a kitten. It spins around, leaps back over the pressure ridge, jumps into the water, swims like crazy to another floe, runs across the floe, dives back into the water on the other side, gets back onto another floe ... we followed him for thirteen minutes before he finally sets the calf down, puts his paw on it, looks around, and then reaches down and delivers the killing bite.

"Meanwhile, mom has risen in the water and she is bellowing like crazy, swimming round and round, making heart-rending bellows, calling and calling. It was very clear as soon as it grabbed the calf, that bear knew he had to get out of there, because he did not want to deal with mom. He really made good distance before he even took the time to kill the damn thing."

Most animals are to some degree risk-averse, their lives a constant cost/benefit analysis. A squirrel in the tree may see a pile of tasty nuts that has fallen to the ground; consuming them would alleviate those hunger pangs and provide a great deal of energy, but being on the ground might leave the squirrel far more vulnerable to a surprise attack from a fox or a bird of prey. Similarly, although they are unquestionably at the top of the Arctic pecking order, even polar bears are aware that they are not invulnerable. A walrus calf will yield a good many calories; it is relatively large and wrapped in a thick coat of desirable blubber. But an attempt to procure one may come at a terrible cost, exacted by a defensive and dangerous mother that may weigh two or three times as much as the would-be predator.

But while polar bears certainly have the option of seeking less dangerous prey, less dangerous does not necessarily translate to less resistant to capture. Polar bears prowl the pack, searching cracks and leads in the ice for seals that are coming up to breathe, but have no way of knowing in advance precisely where a seal might surface at any given time.

There do appear to be a few ways in which bears can improve their chances.

"If you go along a lead edge, there are often little peninsulas of ice that jut out into the edge, and bears typically seem to go out onto these peninsulas and wait," says Kelly. "And the seals seem to surface disproportionately near these peninsulas, and the bears will just snatch them right out of the water."

Even so, while life in the Arctic involves inherent uncertainty, a life spent sitting on ice floes and gazing longingly into open water would suggest one of positive irresponsibility. So polar bears diversify. They look not just for seals in the water, but for those that are resting on the ice along the edge. Hunting seals that have hauled out is in many ways an easier proposition: the seals stand out against the ice, and particularly during periods of pupping, there is an abundance of tasty morsels with neither sufficient awareness nor ability to escape on a consistent basis. Outside of that window, however, the seals that bask on the ice are the seals that, by and large, have survived long enough to be fully aware of the threats polar bears pose. Even when resting, they are wary and constantly on the lookout.

Were success dependent solely on being prescient enough to select the spot where a seal was about to come up for air or rest, or stealthy enough to catch by surprise any seal that had already done so, it is entirely possible that the ursine experiment in the Arctic might never have extended far beyond a few curious brown bears walking out onto the ice from time to time while looking to supplement their diet. Fortunately for our protagonists, there is one seal species that developed biological and behavioral traits that enabled it to survive and thrive in the Arctic for millions of years, but that also rendered it uniquely vulnerable to the monster that ambled over the horizon and shattered the predator-free calm of eons.

On the face of it, a ringed seal does not look very obviously more appealing to a polar bear than any other seal. At about five feet long and 150 or so pounds, an adult may be as little as 20 percent the weight of a bearded seal and be thus theoretically one-fifth as desirable. Pelage aside, it does not appear markedly dissimilar to most other seals, either. There is, however, one key difference.

At the end of its flippers, a ringed seal boasts five sharp, curved claws. These claws allowed the ringed seal to carve its own unique and lucrative niche in the Arctic marine ecosystem, for whereas other Arctic seals wishing to take a quick breath or a longer breather are obliged to make use of natural openings caused by the constant grinding, crashing, and splitting of ice floes, ringed seals can use their claws to create breathing holes of their very own.

"When the first molecule-thick layer of ice forms on the surface of the ocean, it's no big deal for a seal to push through that to breathe," says Kelly. "But when it gets many layers of molecules thick, when it gets inches thick, a bowhead whale or a walrus may be able to break through, but the small head of a ringed seal can't. So they reach up with these stout claws on their flippers, and they scratch a hole through the ice and poke their nose out to breathe."

As a ringed seal approaches a hole from beneath, it may pause, perhaps swim back and forth once or twice, and as it prepares to head upward and into the open air, it will blow a stream of bubbles ahead of it. The bubbles burst at the surface and in so doing, they clear away any detritus—bits of snow or ice—that may have accumulated. Ringed seals do this, Kelly suggests, not because such detritus blocks their passage but because it blocks their view, and a surfacing ringed seal is very keen indeed to try to ascertain whether anything is waiting for its emergence.

For, as much as the ability to create breathing holes has allowed ringed seals to flourish, it has also painted a target on their collective backs. A ringed seal will typically maintain no more than a half-dozen holes during the course of a season; in theory, all a bear need do is identify the location of a hole and be patient. And polar bears are nothing if not patient.

As fall progresses, snow accumulates on top of the holes, concealing them and insulating them. Ice continues to form, but with the snow's insulating warmth, it does so more slowly now than before. If the snow forms into a drift, a seal can, should it be so inclined, reach up into the snow and begin to carve out a snow cave. The cave functions as a place for the seal to haul out and rest on the ice, and while it may take advantage of the protective den for just a few minutes, it may also stay there for close to twenty-four hours.

Many of the caves, says Kelly, are quite beautiful inside.

"If you put your head in a snow cave and look up, there are these beautiful feathery crystals that hang down," he says. "It's frozen seal breath that's condensing on the ceiling and making these chandeliers, and the crystal light that's filtered through the snow is heavy in the blue spectrum, so the whole thing has a blue glow to it. It's just exquisitely gorgeous. I've looked at thousands of these things and every one of them is like a little chapel."

Some of them become not just chapels but maternity wards. In a fascinating echo of the polar bears' dens, it is in such caves, known as lairs—which, just like polar bear dens, may contain several chambers—that ringed seals give birth to and nurse their young.

Just like polar bears, ringed seal mothers must make their lairs in places where there is drifting snow. On the Arctic sea ice, that is almost invariably on the leeward side of pressure ridges formed by floes that have ground into each other, or where the pack has forced itself up against the fast ice and thrust small mountain ranges into the air.

But while polar bear mothers and cubs rest soundly in their dens, seemingly unconcerned by almost any disturbances that may pass by outside their cocoon, ringed seal mothers enjoy no such security. For patrolling the ice outside their snowdrifts, there is a very real threat.

The abundance of seal pups, and the inability of those pups to recognize or react to the danger posed by the prowling predators, makes springtime a time of plenty for polar bears, the time of year when food is both most plentiful and most vulnerable. (Their second most productive period, it seems, is early in the winter, when the rapidly freezing ice forces ringed seals to return to their breathing holes with great frequency to keep them open.)

The surface of the sea ice becomes a study in bear bacchanalia, polar bears feasting almost at will as they sniff out and crash through the lairs that have been painstakingly carved into drifts. It is a testament to the evolutionary and ecological success of ringed seals that, despite the massacre that is visited upon their young every spring, they continue to thrive.

The feeding frenzy is necessary; by the time the gorging is over, spring is well advanced and summer is fast approaching. The sea ice splinters, breaks apart, and melts; the watery leads become chasms in which seals can surface without fear of assault.

The bears are forced to retreat to ice that is thick or sheltered enough to persist during the warmer months, or even onto land, to await the time when temperatures drop once more, when the surface of the water freezes anew, and when they can once more wander, for mile upon uninterrupted mile, across the sea ice that is their unchallenged domain.

Alone except for each other,
the young polar bears face the most difficult period of their lives. If they survive to full adulthood, the age of five or six when they become sexually mature, their chances of surviving deep into old age are high; Ian Stirling has written that natural mortality in adult polar bears is so low that they are "virtually immortal." But the two and a half years until that time, after their mother has left them and before they have grown into full-size adults, are fraught with risk and challenge.

For two years they watched their mother, learned from her, and copied her every move—sometimes playfully, sometimes with more serious intent. But even as they began to hunt and kill seals, they did so with less frequency than she did and continued to rely on her milk for sustenance and certain survival. Now that option is no longer available to them.

They at least have the advantage of abundance, for the time of year in which they were left to fend for themselves was the same as when they first emerged from the den, when a profuse supply of young seals is theirs for the taking. But they must continue to refine their skills, and rapidly, in order to capitalize on this bounty; they must build up their fat reserves as extensively as they can in order to prepare themselves for the lean times that lie just a matter of weeks ahead. They must display the patience they lacked as occasionally dilettante hunters in their mother's company, expend far more time waiting for seals to emerge from their breathing holes, and not waste the opportunities that present themselves when seals do poke their heads out of the safety of the frigid water below. In the harsh Arctic environment, there is no margin for error.

If dogs dream of chasing slow-moving rabbits through grassy fields on a sunny day, then for a wishful, dozing polar bear, paradise is surely a place in which sea ice cover is plentiful and solid, but patterned with cracks large enough for a lazy seal to poke its head through and linger invitingly.

When it rouses from its reverie, the dozing bear shakes off the snow that has settled gently on it during its slumber and rises slowly to its feet. It sniffs the air, blinks softly, and then, after a final shake of its head, it walks.

The Inuit of northwest Greenland call the polar bear
pisugtooq,
"the wanderer," for that is what it does. When it is not sleeping—and polar bears, like humans, sleep for approximately eight hours out of every twenty-four—it is walking. Its stride is languid, apparently without aim or intent; but it is alert at all times, and the moment it sees or smells a seal on the ice—often from a distance of several hundred yards—its demeanor changes in an instant.

It immediately stops, stands perfectly still, and waits, staring at the seal, sometimes for several minutes, as if sizing up the distance to the prey. Then, slowly but surely, it begins its stealthy march. As it moves forward, the bear lowers its head; once it draws within striking range, it sinks to a semi-crouch.

That polar bears are found throughout the Arctic but nowhere in the Antarctic is evident in the behavior of seals at both ends of the Earth. In the Antarctic, seals that have hauled out onto the ice observe approaching explorers or researchers, whether on foot or ship-bound, with mild curiosity but little if any alarm. Save for the restrictions imposed on such behavior by Antarctic Treaty regulations, it would be quite possible to walk up to a basking seal and not elicit much or even any alarm until close enough to reach out and touch it—and often, not even then. For there are no land predators in Antarctica, and a pinniped on the ice is in danger only if it has chosen to repose on a floe that might be tipped over by an observant killer whale. In contrast, ringed seals in the Arctic are bundles of restless energy, napping for perhaps a minute and then lifting their heads to scan their surroundings for several seconds, their large eyes on the alert for any movement, their sharp hearing tuned to detect anything untoward. As soon as a seal tenses in response to the sight or sound of movement, or merely raises itself onto its front flippers for a precautionary inspection of its immediate environment, the bear freezes in its tracks, able to hold its position without a wobble or a twitch, until the object of its attention, apparently unable to pick out the whitish mass of the approaching menace from the background or detect the gentle padding of its paws on the ice, lays down its head once more.