Polar bear

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For polar bears, climate change diet is a losing proposition, a new study suggests.

The Arctic is shrinking with sea ice. , many polar bears have to move their food on land for parts of the summer. A study looking at Hudson Bay polar bears tried to determine if they could maintain their roly-poly figure, which is required and found that a large number of them lost pounds. is doing, no matter what they do to increase their flesh. The weight

Some bears eat a lot of food — berries, eggs, And even caribou antlers—but it takes so much effort, so many calories are burned trying to eat them, that they lose weight and expend more energy, according to a the study In Tuesday’s Journal Nature Communications.

Other bears go into semi-hibernation, don’t do much, but they also shed pounds, so it doesn’t work either way, said Anthony Pagano, a wildlife biologist with the U.S. Geological Survey and lead author of the study. said

The researchers found that 19 of the 20 bears studied lost an average of 47 pounds (21 kg) during the three weeks they were studied in the study. , Energy use and respiration in the wild. It is losing about 7 percent of them. In just 21 days on average, the study concluded.

Images from polar bear collar cameras document summertime activity, and inform a new research study from the USGS and Washington State University. Polar bears exhibited a wide range of behaviors, from resting 98% of the time on land to traveling up to 330 km (205 mi) over three weeks and spending up to 40% of their time grazing on berries. Ultimately, all bears, except one individual that found a marine mammal carcass on land, lost an average of about 1 kg (2.2 lb) per day, highlighting that none of these behavioral strategies It was not beneficial to extend the period in which polar bears can. survive on earth. Credit: US Geological Survey and Washington State University

Polar bears try to maintain their weight in the summer after spring when they eat and fatten up spectacularly. Pagano said that in the Hudson Bay region where the researchers studied, the lack of sea ice means that polar bears are on land three weeks longer than they were in the 1980s.

In general, polar bears eat fat seals while at the base of the sea ice, close to where the seals are. Pagano said it’s especially good hunting in the spring when the seal pups are weaning and learning to swim through the ice base before being easy pickings for polar bears.

Last September, when Arctic sea ice reached its annual low in September, there was about 1 million square miles (2.6 million square kilometers) less sea ice than at the same time in 1979. National Snow and Ice Data Center. The United States Fish and Wildlife Service lists polar bears. An endangered species “due to the loss of its sea ice habitat

“This paper clearly shows that polar bears cannot keep up with the pace of change in the Arctic and that bears are already using everything they can to survive,” University of Alberta biologist Andrew said DeRocher, who was not part of the research. , but called it deeply beautiful and insightful.

“It’s concerning because of course it raises the question of when individual bears will run out of energy,” DeRocher said. While the research showed that some bears would be fine, “other bears were basically on the edge where they would likely starve and die as a result.”

Overall, this shows that polar bears may not have adapted to living on land, Derocher said.

When polar bears have sea ice, they feed on seals. Not just seals, but their fat. About 70 percent of a polar bear’s diet while on the ice is fat, said study co-author Karen Rudd, a USGS wildlife biologist.

“They have the highest fat diet of any species in the world,” Rudd said.

“Polar bears need sea ice for food—that’s how they have access to their primary prey (ice seals),” said University of Washington biologist Kristen Ledery, who was not part of the study team. do to subsist on fatty seafood and have a remarkable ability to utilize and digest lipids.”

To find out what happens on Earth, a joint US-Canadian team of biologists put video on bear collars, fed the bears a type of water that could track their caloric intake and expenditure. And they were returned to the forest to see.

Hunting bears for food was impressive. All but one of them ate grass and kelp, 10 of them fed on berries, eight of them chewed on bird carcasses, one-third of them chewed on bones, and four of them ate caribou. Also ate a horn, bird’s eggs, a mouse and a rabbit. ate

But the bears had to expend a lot of energy trying to fill their stomachs. On average they traveled 58 miles (93 km), with one young woman covering 233 miles (375 km) in three weeks.

“This paper adds to a growing body of evidence. cannot sustain themselves on land because we continue to lose sea ice due to climate warming,” said Ledery, who heads the International Union for Conservation of Nature’s polar bear expert group, which Monitors the status of endangered species.

More information:
Anthony Pagano, Energetics and Behavioral Strategies of Polar Bears with Implications for Survival in an Ice-Free Age on Earth, Nature Communications (2024). DOI: 10.1038/s41467-023-44682-1. www.nature.com/articles/s41467-023-44682-1

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Reference: For Endangered Polar Bears, Climate Change Diet Is a Losing Proposition (2024, Feb 17) Accessed 17 Feb 2024 at https://phys.org/news/2024-02-threatened-polar-climate-diet- Retrieved from proposition.html

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