High-tech cameras suggest polar bears having tougher time hunting

Kristen Gonzales
February 2, 2018

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

Scientists studying the metabolism of free-ranging polar bears in the Arctic have found out why the loss of sea ice is hurting their survival: They burn calories at a faster rate than previously thought.

One bear lost close to 44 pounds, including her lean muscle, in 10 days.

Polar bears could be sliding towards extinction faster than previously feared, with the animals facing an increasing struggle to find enough food to survive as climate change steadily transforms their environment. Eight to 11 days later they were all re-captured.

"They need to be catching a lot of seals", Anthony Pagano, a Ph.D. candidate at the University of California at Santa Cruz, said in a statement.

The movement of nine bears was tracked by human observation and Global Positioning System tracking collars as they hunted for food across hundreds of kilometres of Beaufort Sea ice offshore Prudhoe Bay, Alaska.

"This study is a lovely example of how animals are built to live in synchrony with their environment".

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.

It doesn't help that the loss of sea ice means that polar bears have to work harder to stay where the food is, Whiteman pointed out.

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 equipped the bears with GPS-enabled video cameras as well as with instruments to measure the speed and distance they travelled, how quickly they burned energy and how much time they spent in the water. "Eventually, you run out of gas".

Meanwhile, the most recent polar bear population estimate by USGS also indicated almost 40 percent decline over the past decade. "But continued research is needed to understand the climate-related pressures that polar bears face".

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Millions have seen the heart-wrenching video of a polar bear clinging to life, its white hair limply covering its thin, bony frame.

Scientists once thought that polar bears should be able to reduce their metabolic rates when there's not much food available.

The cameras recorded footage of bears catching seals and hauling them out of the ice, as well as of bears wrestling with large seals in frigid waters.

Polar bears rely nearly exclusively on a calorie-loaded diet of seals.

"Some bears were able to catch seals and put on a lot of mass and fat", Pagano said.

They then tracked their hunting strategies and how far they moved as they crossed the Beaufort Sea ice fields in April of 2014, 2015 and 2016.

Even though the Arctic should be flush with seal pups in the month of April, the researchers found numerous bears were spending more energy chasing down prey than they consumed.

Polar bears wait for their prey to come to them. Less area to hunt means lower body condition for bears, which means fewer healthy cubs, which means a decline in population.

Pagano said the working assumption is that as the ice recedes and the bears move further North following receding ice, they will move over deep water that is less conducive to seal hunting. The agency's most recent population estimate suggests the bears have declined by about 40 percent over the past decade.

Every year in the Beaufort Sea, the sea ice begins to retreat north in July.

"Arctic communities are not prepared to deal with such a spill, and when it happens the contaminants will have long-term impacts on important habitat for wildlife, including polar bears, whales and fish", said Paul Crowley, vice president of Arctic conservation for WWF-Canada, in a scorecard that included nation-by-nation evaluations in areas such as management of human and polar bear conflict.

Other reports by TheSundaySentinel

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