Polar Bears in Svalbard Became Fatter and Healthier, Despite Disappearing Ice

Polar bears hunt seals on sea ice, which is their main source of fatty food. The bears' fat reserves provide them with energy and thermal insulation, and also allow females to produce nutritious milk for their cubs.

Between 1992 and 2019, scientists weighed and measured 770 adult bears in Svalbard and found that they had become significantly fatter.

They believe that the bears have adapted to new conditions by hunting more terrestrial animals, such as reindeer, as well as walruses.

This discovery, which scientists reported in the journal Scientific Reports, seems particularly surprising given how strongly climate change affects Svalbard.

During the period of this study, the rise in global temperature led to the length of the ice-free sea season in this region increasing by almost 100 days — it grew at a rate of approximately four days per year.

"The fatter a bear is, the better off it is," explained Dr. Jon Aars, a lead researcher at the Norwegian Polar Institute. "And I expected that with such a significant reduction in sea ice area, the animals' condition would worsen."

In Norway, walruses have been officially protected since the 1950s, as they were on the verge of extinction due to hunting before that. The protection has helped increase their numbers, and apparently, walruses have become a new source of fatty food for polar bears.

"Today, there are significantly more walruses around," says Aars. "Perhaps they have also learned to hunt seals more efficiently."

He explained that when there is less ice on the sea, seals gather in smaller areas, making it easier for bears to catch them.

Although this is unexpectedly good news for these Arctic predators, researchers believe that this situation is unlikely to last long.

Павялічыць

As sea ice continues to shrink, bears have to travel ever-greater distances to reach hunting grounds. This means they expend more energy and lose valuable fat.

As the charity Polar Bears International reminds us, polar bears in Svalbard were actively hunted until the 1970s.

These animals were then placed under international protection, and experts believe that this, along with the increasing numbers of walruses and reindeer, may also have influenced the population's condition.

However, this improvement in the bears' condition, researchers believe, may only be temporary.

"Body condition is only part of the picture," says Dr. John Whiteman, a lead specialist at the Norwegian Polar Institute. "Another recent study showed that an increase in ice-free days reduced the survival rate among cubs, subadult bears, and old females."

In other regions of the Arctic, climate change affects polar bear populations quite differently. There are 20 of them in total.

The southernmost and most well-studied of these is the population in western Hudson Bay in Canada. Its numbers are declining, and scientists directly link this to warming.

According to Dr. Whiteman, in the long term, the picture is clear: polar bears need the sea to freeze to survive.

"The reduction in ice area ultimately leads to a reduction in the number of bears, although [as this latest research shows] the short-term picture can vary greatly from region to region," Dr. Whiteman told the BBC.

"In the long term, however," the scientist continued, "if the reduction in ice area is not curbed, polar bears will eventually disappear."

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