Polar bears, the apex predators of the Arctic, need more fat-reach food than previously thought, but melting sea ice in the region makes it hard for them to meet their energy needs, a new research has revealed. That has ominous implications for a future in which sea ice is ever scarcer.
USA scientists captured and fitted collars equipped with Global Positioning System and "bear cam" to nine cub-less female bears. Less area to hunt means lower body condition for bears, which means fewer healthy cubs, which means a decline in population.
"We found that polar bears actually have much higher energy demands than predicted". However, it seems these savings are small at best.
Pagano's team studied the bears in a period during April over the course of three years, from 2014 to 2016, in the Beaufort Sea off Alaska.
Their energy consumption as calculated during the study was 1.6 times higher than previously thought.
But, the bears are likely to have.
Photos of skinny and emaciated polar bears are more common as their food disappears
Unfortunately, with the rapid environmental changes occurring in Arctic sea ice, the specialisation that once allowed polar bears to live in this challenging habitat has painted the animals into a physiological corner and led to devastating consequences.
Though Pagano's study focuses on just, numerous other populations around the Arctic likely face the same challenges, says Derocher.
Andrew Derocher, a polar bear biologist at the University of Alberta, warned that there is wide variability between bears and different times of year.
Analysis of the bears' metabolism revealed they required at least one seal every 10 days to satisfy their dietary needs, but numerous bears were unable to capture enough.
The vision of a polar bear plucking a vulnerable seal off an ice floe is something familiar to wildlife documentary fanatics.
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"It's an issue of how much fat they can put on before the ice starts to break up, and then how much energy are they having to expend", Pagano said. Bears are also doing a lot more swimming as the sea ice declines, said Derocher.
Millions have seen the heart-wrenching video of a polar bear clinging to life, its white hair limply covering its thin, bony frame. "Activity and movement on the sea ice strongly influenced metabolic demands", the researchers summarized in the abstract of their paper.
"When scientists say bears are going extinct, I want people to realise what it looks like".
Researchers have been studying bears in the Beaufort Sea since the 1980s and studies have shown the population there has decreased by some 40 percent during the last decade.
"The chain of logic that everyone is concerned about is that the melting of sea ice reduces the amount of time that bears get to spend on sea ice in the productive regions where seals are concentrated", said Professor Whiteman, who wrote a commentary in Science.
All over the Arctic, scientists have seen evidence of weakened polar bears, Pagano said.
But more tracking and monitoring will be necessary to fully understand what's happening to the bears.
"Two-thirds of the world's polar bears could die out by 2050", cautions WWF, demanding an immediate decline in greenhouse gas emissions so the bears can stand a chance of survival.
"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.
"While the Canadian government has made impressive progress in polar-bear science and policy, there is only so much that can be done on such a limited budget".