This means they need more prey, primarily seals, to meet their energy demands at a time when receding sea ice is making hunting increasingly hard for the animals.
The researchers used high-tech collars on the bears to record video, locations and activity levels over a period of eight to 11 days. "This and other studies suggest that polar bears aren't able to meet their bodily demands like they once were". Their most recent population estimate indicates the polar bear population has declined by about 40 percent over the past decade.
Polar bears are listed as Vulnerable on the International Union for Conservation of Nature's (IUCN) Red List of Endangered Species and listed as threatened by the US Endangered Species Act.
Researchers counduct the year-long study on nine female white giants and monitored their weight and blood during the spring. 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.
Polar bear wearing Global Positioning System collar on sea ice.
New information from an American study shows polar bears may be under greater threat from climate change than previously thought.
"As they reduce that amount of time it follows that they catch fewer seals total and they are taking in a lower amount of energy". These majestic animals use sea ice as a platform from which to hunt their fatty, energy-dense prey: seals.
"The objective was to get a better understanding of what the changes in sea levels are and how they are impacting the polar bears", Anthony Pagano, a lead researcher in the study, told CNN. Scientists blame climate change for shrinking the ice cover on the Arctic Ocean that the polar bears need for hunting.
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The researchers hypothesize that the bears' lazy hunting style - when it works - allows them to conserve energy, helping them survive through the summer months when food is scarce. The researchers went there and observed the bears. One bear lost 51 pounds (23 kilograms) in just nine days.
Improvements in animal research technology gave us an opportunity to gain insight into the metabolism, behavior, foraging success and movement patterns of polar bears on sea ice.
Canada, home to two-thirds of the world's population of roughly 30,000 polar bears, has done a good job surveying subpopulations, making sure the polar bear trade is legally regulated, and incorporating traditional knowledge into polar bear management, the WWF said.
While scientists were quick to caution that the causes of the animal's condition remain unknown-disease, injury or any number of other factors could potentially have spelled its demise-experts are anxious that starving polar bears may soon become a more common sight as the sea ice they rely on for hunting grounds continues to melt away. During that time the bear crossed into Canada, having walked almost 270 miles (430 kilometers) since her collar had been applied.
By catching their favourite prey - ringed seals - every 10 to 12 days, a female polar bear will maintain weight levels of around 450lbs, yet the challenge of fulfilling a consumption rate of 220 Big Macs over this short period is becoming increasingly fraught.
Satellite telemetry shows several tagged polar bears moving long distances to remain on receding sea ice in July 2016.
A new study finds the large predators have a higher metabolic rate than previously expected and prey is getting harder to catch as climate change causes sea ice to retreat sooner than ever.