Climate change is making polar bears go hungry, study finds

Mindy Sparks
February 2, 2018

Researchers have attached tiny cameras to polar bears for a bear's-eye view of them hunting on the sea ice, one of a suite of high-tech tools providing what could be the closest look yet at how the iconic animals are coping with a rapidly changing Arctic.

Wrong, said Pagano. His study concludes bear metabolism is about 60 per cent higher than previous estimates, meaning the animals need to eat that many more seals to maintain weight. "This study identifies the mechanisms that are driving those declines by looking at the actual energy needs of polar bears and how often they're able to catch seals".

According to recent measurements, the extent of Arctic sea ice is decreasing at a rate of about 14 percent in every 10 years, which can significantly reduce polar bears' access to seals.

The team also measured the energy cost of activities such as walking and hunting, and monitored changes in the animals' body mass over 8 to 11 days, says Anthony Pagano, a biologist at the US Geological Survey's Alaska Science Center in Anchorage who led the research.

But certainly, vanishing sea ice makes the predators' hunt for seals more hard.

Nasa has estimated that September sea ice levels are declining at a rate of 13 per cent per decade, with potentially devastating consequences on polar ecosystems. The only way for the bears to restore that lost energy was to catch more seals.

While those Arctic ocean bears need ice in order to hunt for food during the spring, global warming is dwindling the blanket of ice across the locale.

He and his colleagues studied nine bears in the Beaufort Sea over the course of about a week during three successive Aprils from 2014 to 2016.

"I hope we will have an awakening, but we haven't really done much to save polar bears over the past decade", said Amstrup.

Though polar bears are known to live a "feast or famine" lifestyle, in which their weight fluctuates considerably, the creatures should have been gaining weight during the period studied, rather than losing it.

"That has a cost, and the animal has to find the energy to do that - or take it out of growth, reproduction, or survival", says polar bear biologist at the University of Alberta in Edmonton, Canada.

Until then experts had assumed that polar bears required less energy because they have no natural predators and their hunting method does not involve a lot of physical exertion: They sit on ice floes and wait for seals to emerge.

Weighing up to 1,200 pounds, polar bears are the largest land mammals in the Arctic, though they are classified as marine mammals because they spend so much of their time in the water. That's four times the weight they would've lost if they were on land not going after seals. By fall, however, young seals are older and wiser, and the bears can not catch as many of them.

Best estimates say there are 20,000 to 30,000 polar bears in 19 different groups or populations scattered across the top of the U.S., Canada, Greenland, Norway, and Russian Federation. A few of the bears travelled more than 155 miles (250 kilometres ) in about 10 days off the northern coast of Alaska in the Beaufort Sea, Pagano said. Shot by Paul Nicklen and Cristina Mittermeier of the nonprofit group Sea Legacy, and published on National Geographic in early December, the video ignited a firestorm of debate about what scientists know, and don't know, about the impacts of global warming on polar bears.

Other reports by Iphone Fresh

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