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.
A high fat diet based on blubbery seals is essential for providing the necessary energy for the bears to live in the cold, but sea ice changes have made it harder to find this critical prey, Williams said.
They collared nine adult female polar bears on the sea ice of the Beaufort Sea in Alaska with a Global Positioning System video camera and observed the bears for discreet time periods over three consecutive years. "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", Anthony Pagano of U.S. Geological Survey, now a Ph.D. candidate at University of California, Santa Cruz and first author of the paper, said in a statement Thursday.
Retreating ice sheets, a result of climate change, are forcing the bears to travel greater distances to find the food they need, which in turn causes them to expend more energy than in the past, the study said. Their energy consumption as calculated during the study was 1.6 times higher than previously thought.
While four bears put on weight, five bears lost up to 10 per cent of their body weight - between 18 and 20 kg - in 10 days.
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. "And if they don't do that they're going to lose weight".
In December a year ago, a video of a dying polar bear rummaging in trash and eating styrofoam, assumed to be starving, went viral on social media.
Because polar bears are primarily "sit-and-wait" hunters, patiently biding their time at air holes seals use to breath, researchers believed their metabolic output was relatively low. Data shows from 2004 to 2007 polar bears population in the Beaufort Sea has been gone down by 40 percent.
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The study shows that global warming is the reason which has treaten their existence and stopping them from hunting seals during spring.
"When you're talking about some places extending their melt season to double digits by the end of the decade we're not that far out from that kind of lengthening of the melt period in some parts of the Arctic", he said.
Earlier this winter, though, an image of an emaciated polar bear went viral, with many asking if this was the telltale image of climate change.
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.
"Just to break even they have to capture at least one seal every five to 10 days - and that's just to break even", said study co-author George Durner, a USGS research zoologist.
And the bears' challenge to survive is only likely to increase as sea ice coverage continues to decrease.
"Nobody can conclude from the study that polar bears will get extinct", he tells DW.