American Elephants

The Polar Bears Are Just Fine! by The Elephant's Child


Biologist Susan Crockford gives us ten good reasons not to worry about polar bears.

1. Polar bears are a conservation success story. Their numbers have rebounded remarkable since 1973, and there are more polar bears now than there were 40 years ago. Polar bears join a long list of marine mammals whose populations rebounded spectacularly after unregulated hunting stopped: sea otters, all eight species of fur seals, walrus, elephant seals, whales (grey, right, bowhead, humpback, sei, fin, blue and sperm whales.

2. The only polar bear subpopulation that had a statistically significant decline in recent years is the one in Western Hudson Bay. A few others have been presumed to be decreasing based on suspicions of overharvesting, assumed  repercussions of decreased sea ice and/or statistically insignificant declines in body condition— not actual population declines.

Figure 1. A map of the 19 polar bear subpopulations (courtesy the Polar Bear Specialist Group (PBSG), with a few additional labels).

3. Sea ice in the Bering Sea has rebounded from record lows over the last ten years, a good reason not to be worried about polar bears in the Chukchi.  A recent survey suggests that Chukchi bears are doing very well. Sea ice coverage has been higher than average.

4. A survey by the Nunavut government in 2011 showed polar bear numbers in Western Hudson Bay have not declined since 2004 as predicted and all available evidence indicates that Hudson Bay sea ice is Not on a steadily precipitous decline.

5. Population decreases in bear numbers attributed to earlier sea ice breakup in Western Hudson Bay have not been anywhere near as severe as the catastrophic decline that took place in 1974 in the eastern Beaufort Sea, which was associated with exceptionally thick sea ice.

6. Polar bears need spring and early summer ice (March through June) for gorging on young, fat seals. Documented declines in sea ice have rarely impinged on that critical feeding period.

7. There is no plausible evidence that regulated subsistence hunting is causing polar bear numbers to decline.

8. Global temperatures have not risen in a statistically-significant way in the last 16 years, a standstill not predicted by climate models, and a phenomenon even the chairman of the IPCC has acknowledged. This suggests that the record sea ice lows of recent years are not primarily due to CO2-caused increases in global temperatures. Such changes in Arctic sea ice appear to be normal habitat variations that polar bears have survived before.

9. Survival of polar bears over a hundred thousand years of variable sea ice coverage indicates that biologists who predict a doomed future for the bears have grossly underestimated its ability to survive vastly different conditions than those that existed in the late 1970s when Ian Stirling began polar bear research.

10. Polar bears are well-distributed throughout their available territory, which is a recognized characteristic of a healthy species.

Polar bears have evolved into a highly efficient predator of ice-associated seals. They are excellent swimmers compared with other bear species, the use the sea ice to travel, hunt, mate and rest. They have adapted to the annual loss of sea ice in the summer by migrating onto land. While there, they cannot hunt seals and must rely on their fat reserves to see them through until the ice returns. Though I assume they eat fish and berries.

Polar bears can swim for long distances (60 miles or more). Arctic sea ice grows in the winter and melts in the summer. Polar bear science is surprisingly new, and there is much that we don’t know about the species yet. Counting them is hard and inaccurate.Female bears have been tagged, but you can’t collar male bears as their necks are bigger than their heads.

The bears are very beautiful, and the cubs cute as can be, which is probably why environmentalists got all panicky about declining numbers. In general many  supposedly endangered species turn out not to be endangered. Many times declining numbers are due to unregulated hunting or uncontrolled predators. Preservation of species is complicated,  and we’re just beginning to get the hang of it. This is derived from a much longer and more informative post at Anthony Watts’ wonderful What’s Up With That website, which explains sea ice and  what we know about bears and climate.



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