The young woman was intense as she cornered the professor who had just spoken, and made her case. She passionately argued that polar bears could survive the loss of sea ice that has been so well documented over the past few decades. Sure the animals were losing weight, cubs were dying or not being born, adults were drowning at sea. But she had been up north, had seen polar bears eat things other than seals. They would survive.
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(Photograph by Sophie Lumsden)With patience the professor tried again to explain what he had said in his talk, given during an international conference on bears I had attended in Ottawa, in July. He said that, for example, with snow goose populations at very high levels some thought that their eggs, easy pickings, could fuel polar bear appetites, but research showed that even if every goose egg were eaten it would not provide enough calories to save the polar bears. You see, they are not so much meat eaters as they are fat eaters, and they require a percentage of fat so high in their diets that only seals can provide it. And the most important kinds of seals, because they are accessible to female polar bears, are ringed seals and, to a lesser extent, perhaps harp and hooded seals. Those seals are dependent on ice for the production of young, and it is the young of the ringed seal that forms the key component to the female polar bear’s diet, and that of her young.
It’s more complicated than that, of course, but the thing to remember is that the polar bear has become highly specialized. Unlike grizzly bears, they cannot survive from a wide variety of food. They need large amounts of fat in their diets and key periods in their breeding cycle, and only the seals provide it. Ringed seals make little den-like enclosures on top of the ice, and that is where they give birth. Polar bears find these dens, enough of them, and break through them to obtain their prey. But with the rapid decline in ice, all very carefully measured and documented over recent decades, there has been a subsequent decline in the presence of these dens. Ringed seals are in decline. Yes, polar bears can still find things to eat, the young lady was correct about that, but not enough fat to allow them to thrive and give birth and raise baby polar bears.
In some areas the receding ice has disappeared from food-rich inshore waters, and only occurs farther out, off shore, over deeper waters where there are fewer fish, which seals eat, thus fewer seals. The seals aren’t extinct, but their numbers are in decline and no one has funded the research to allow us to know by how much. It would be a difficult thing to determine.
And as if all that weren’t enough, the reduced ice has opened up channels for an increase in orcas, a.k.a. killer whales, which compete with the polar bears for seals, and even can eat polar bears! Add in the increased shipping and oil exploration, pipelines and conflicts with people — such as the starving polar bear who killed a teenager camper on the Norwegian island of Svalbard last week, and was subsequently shot — and, well, I am not at all hopeful that the species can survive through to the end of the century, or much beyond.
Earlier that week I had been examining the remains of prehistoric, ice-age fauna at the National Museum of Natural History, and I guess that experience had brought home to me just how perilous it is for highly specialized species to survive when their environment undergoes rapid change. Large numbers of very large animals — giant bison, large beaver, the dire wolf, the huge short-faced bear, the sabre-toothed cat, horses and camel-like creatures, mastodons and mammoths and many more — had all become extinct right here in Canada during change near the end of the last ice age. It is not unusual for large, specialized animals to become extinct in the face of change; it is usual. It is normal. It is what is to be expected, and nothing is being done to stop it from happening.
Let’s hope I’m wrong. I won’t live to know, but having seen wild polar bears I fear that I’ve experienced something that will be forever unknown to future generations of my own kind.
Blogging off,
Barry