A recent study of 45 years of observation data on polar bears shows that the animals collect the bodies of murders, bury them in the snow or dirt, so that they can return to them later.
The behavior, called caching, is relatively common in other types of bears, in particular brown bears, from which polar bears emerged around 500,000 years ago.
The behavior is exceptionally rare with polar bears, but Ian Stirling from the University of Alberta and the Polar Bears Scientific Advisory Board decided to investigate it after receiving an intriguing photo from a friend.
A team of scientists reviewed observation data of polar bears taken between 1973 and 2018, and found only 19 cases of a bear burrowing its dead after being unable to eat it at once, observed a rare behavior in only 0.5 of the bears
“My curiosity about short-term food caching was reactivated by receiving a photo from a friend of a male polar bear lying on the ice with a snow-covered harp seal,” Stirling told Polar Bears International.
“I had only seen this type of behavior once in more than 40 years of research into polar bears.”
For his research, Stirling assessed observation data of polar bears taken between 1973 and 2018 in Svalbard, Greenland and the Canadian Arctic, and found only 19 cases of caching with deaths of only 0.5 percent of the bears observed.
Polar bears live on a diet of mainly seal meat and can eat between 10 and 20 percent of their own body mass at once.
The average adult polar bear weighs around 1200 pounds, while adult harp seals weigh between 265 and 300 pounds.
The assessed data consisted of video, photos and logs of bear behavior taken in the Canadian Arctic, Greenland and Svalbard, a Norwegian archipelago in the Arctic
In rare cases where a polar bear was unable to eat a seal he had recently killed, he sometimes buried him in the ground and guarded the site against other predators, a common behavior among other species of bears, but one that has rarely been documented under pool bears
This inequality means that a polar bear cannot eat a whole seal in just one go, or would not eat it.
When those rare circumstances occur, polar bears will bury themselves in the snow or dirt to hide their dead, then cover it with snow or more dirt to make it difficult for other bears who can randomly choose.
Some bears were observed lying over their buried murders, unwilling to keep them out of sight, but also unable to eat them completely.
Polar bears can eat between 10 and 20 percent of their 1,200 pound body weight at once, and seals, which are their main food source, are rarely too big to eat
Researchers suggest that behavior can be so rare because bears live in relatively underpopulated areas, with fewer scavenger species and other bears to compete with for food sources
“In short, the fat and meat of smaller seals, such as ringed or ringed puppies, are largely devoured immediately and leave little to hoard,” Stirling said.
“The carcasses of adult seals, harp seals and bearded seals, on the other hand, can be covered with snow to reduce the risk of valve parasitism. [theft] by another bear or scavengers who visually detect a dark spot on the ice while the hoarding bear is close by. “
A possible explanation for the fact that the cache of polar bears kills so much less often than brown bears is that they live in less densely populated areas.
Brown bears usually live closer to other bears, as well as important populations of scavenger species such as crows.
WHY DO I HAVE ICEBERNS ICE TO SURVIVE?
Loss of ice due to climate change has a direct impact on polar bears’ ability to feed and survive.
The bears need ice platforms to reach their prey of ringed and bearded seals. Some sea ice lies over more productive hunting grounds than others.
Like other predators at the top of the food chain, polar bears have a low reproduction speed. One or two cubs are born in the middle of winter and stay with their mother for two years.
Consequently, females only breed every three years. The bears do not reproduce until they are five or six years old.
From late fall to spring, mothers with new cubs in snowdrifts on the land or on pack ice. They come out of their caves, with the new cubs, in the spring to hunt seals on floating sea ice.
Simply put, if there is not enough sea ice, seals cannot drag on the ice and polar bears cannot continue to hunt.
Measurements at the end of the summer of sea ice in the Arctic in September showed that the region has reached the eighth lowest degree in modern administration.
Satellite data showed that the Arctic reached its lowest annual level on September 13, at 1.74 million square miles (4.64 million square kilometers).
While the Arctic reaches its minimum in the summer every year around that time, the experts say that the size has declined rapidly as a result of climate change, and has seen dramatic decline since the end of the 1970s.