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Climate Change Fires Up Polar Bear Treadmill¹

气候变化害苦了北极熊

Polar Bears spend most of their time roaming the sea ice in search of seals. And seals spend most of their time underneath² that ice, avoiding the top predator³. But climate change is giving polar bears additional challenges in their searches for food.

北极熊大部分时间都在海冰上漫游，寻找海豹。而海豹大部分时间则都呆在冰层下，避开冰层上的捕食者。但气候变化给北极熊觅食带来了额外的挑战。

“Sea ice is now drifting faster.” George Durner is a research zoologist⁴ with the United States Geological Survey Polar Bear Research Program. He and colleagues compared sea ice conditions from 1987-1998 with those from 1999 to 2013.

“海冰现在漂得更快了。” 乔治·德纳——美国地质调查局北极熊研究项目组的一名研究动物学家。他和他的同事们将1987年至1998年的海冰状况与1999年至2013年的海冰状况进行了对比。

\“And what we found was ice drift at the locations used by polar bears increased 30% in the Beaufort sea and 37% in the Chukchi sea.” That’s a problem because polar bears are homebodies—they prefer to stay in a specific range.

“我们发现，在波弗特海地区北极熊使用的漂冰增长了30%，而在楚科奇海地区则增长了37%。”这是一个问题，因为北极熊是居家型物种——它们喜欢呆在一个特定的范围内。

“Throughout their range, they seem to have a sense of place. And … here we have a situation where the general pattern of ice drift is westward⁵, so to remain in your traditional range, it means you have to constantly be walking eastward⁶ to compensate⁷ for that westward drift.”

“在它们的生活范围内，它们似乎会有一种归属感。然而……这里面临的情况是，漂冰一般是向西漂流的模式，所以留在它们本来生活的范围内，就意味着它们必须不断的向东行走，以弥补漂冰的向西运动。”

The result: a large-scale polar bear treadmill. And all that walking requires extra fuel. On average, a single bear eats between 31 and 33 seals per year. But the metabolic⁸ consequence of the treadmill effect means they have to eat on average one to three more. The study is in the journal Global Change Biology.

结果就是：大规模的北极熊徒步迁徙。而这种徒步迁徙需要额外的能量。平均来说，一只北极熊每年会吃掉31到33只海豹。但徒步迁徙带来的代谢后果意味着它们平均要多吃一到三只海豹。这项研究发表在《全球变化生物学》杂志上。

And not only is the ice drifting faster—it’s also melting more, giving the bears less of the platform they use to pursue their prey⁹. So they need more seals but have a tougher time tracking them. All of which puts polar bears on a slippery slope.

然而海冰不仅漂流得更快了，它融化的也更多了。这使得北极熊可用的用来追捕猎物的平台变得更少了。因此，北极熊需要捕猎更多的海豹，但追踪海豹却变得更加困难了。所有这些都使北极熊的境地越来越糟糕。