United Kingdom

Polar bears use ice blocks and boulders to bludgeon unsuspecting walruses

Polar bears make use of blocks of ice and boulders to bludgeon unsuspecting walruses on the head and aid in hunting them for food, a new study revealed.

Walruses can weigh as much as 2,800lb, making them a tasty treat for polar bears, but with huge tusks and a thick skull, they are a risky and difficult kill. 

Anecdotal evidence from Inuit tribes has long suggested that some polar bears get through the nearly impenetrable skull of a walrus using heavy objects as a weapon.

These accounts are usually dismissed by scientists, but after a polar bear in a zoo in Japan used tools to obtain suspended meat, leading polar bear expert Ian Stirling and colleagues from the University of Alberta decided to investigate further.

'If an experienced Inuit hunter tells you that he’s seen something, it’s worth listening to and very likely to be correct,' Stirling told ScienceNews. 

They reviewed observations by Inuit hunters, explorers and naturalists to confirm that tools were infrequently used by polar bears, specifically in hunting walruses.

Polar bears make use of blocks of ice and boulders to bludgeon unsuspecting walruses on the head and aid in hunting them for food, a new study revealed

Walruses can weigh as much as 2,800lb, making them a tasty treat for polar bears, but with huge tusks and a thick skull, they are a risky and difficult kill

POLAR BEAR (URSUS MARITIMUS)

The polar bear (Ursus maritimus) is a carnivorous bear native to the Arctic Circle and surrounding seas. 

They are the largest bear species still alive and the largest land carnivore.

An adult male weighs up to 1,540 lb and an adult female is up to 750lb.

It is a sister species of the brown bear but evolved to occupy a narrower ecological niche, adapted to the cold.

Seals make up most of their diet, but they also hunt for fish and walrus.

There is some evidence that they use ice blocks and boulders as tools to help bring down a walrus for food. 

For thousands of years they have been a major part of the material, spiritual and cultural life of people native to the polar regions and are still important.

They are also traditionally known as the 'White Bear' and as the 'nonook,' a name stemming from the Inuit people. 

Since the 1700s, reports of polar bears using tools to kill walruses have been passed on verbally, according to Sterling.

This was passed to explorers and naturalists by their Inuit guides, based on local traditional ecological knowledge.

There are also more recent accounts of direct observations made by modern Inuit hunters speaking to scientists. 

To assess the possibility that polar bears may occasionally use tools to hunt walruses in the wild, Sterling and his team looked back through archive records to find instances of Inuit hunteers speaking to naturalists about polar bear tool use.

They also looked at a recent observation of a polar bear in a zoo in Japan spontaneously using tools to access a new food source. 

The male polar bear named GoGo used tools to access meat that had been suspended over his enclosure. 

These observations and previously published experiments on brown bears, the closest living relative to polar bears, confirm that, in captivity, polar and brown bears are both capable of conceptualising the use of a tool to obtain a food source that would otherwise not be accessible. 

'Based on the information from all our sources, this may occasionally also have been the case in the wild,' Stirling said.

'We suggest that possible tool use by polar bears in the wild is infrequent and mainly limited to hunting walruses because of their large size, difficulty to kill, and their possession of potentially lethal weapons for both their own defence and the direct attack of a predator.'

Anecdotal evidence from Inuit tribes has long suggested that some polar bears get through the nearly impenetrable skull of a walrus using heavy objects as a weapon

These accounts are usually dismissed by scientists, but after a polar bear in a zoo in Japan used tools to obtain suspended meat, leading polar bear expert Ian Stirling and colleagues from the University of Alberta decided to investigate further

'If an experienced Inuit hunter tells you that he’s seen something, it’s worth listening to and very likely to be correct,' Stirling told ScienceNews

'Really, the only species you would want to bonk on the head with a piece of ice would be a walrus,” polar bear expert Andrew Derocher told ScienceNews.

The director of the Polar Bear Science Lab at the University of Alberta, who was not involved in this study, suspects it is just a handful of bears able to use tools.

He said that a mother bear may have figured out how to use a stone, meaning her offspring would also pick up on the skill by watching their mother.

They reviewed observations by Inuit hunters, explorers and naturalists to confirm that tools were infrequently used by polar bears, specifically in hunting walruses

However, he said it was unlikely that it is a skill all polar bears throughout the Arctic would have. 

Animals using tools to solve problems has been long regarded as a marker of a higher level of intelligence, based on how humans define intelligence.

Chimpanzees have been seen crafting spears to hunt, dolphins using sea sponges to stir sand to find prey and elephants dropping logs on electric fences. 

Studies into the cognitive abilities of polar bears has been lacking, according to Stirling, who said we 'don't know anything experimental or objective at all'. 

Since the 1700s, reports of polar bears using tools to kill walruses have been passed on verbally, according to Sterling

They had to rely on subjective evidence and observations to confirm polar bears make use of rocks and ice blocks specifically for the purpose of taking down prey. 

“However, we have a great deal of observational information that tends to suggest polar bears are really smart,' Stirling told ScienceNews. 

Members of the bear family have large brains in comparison to many other mammals and, combined with sophisticated hunting strategies, it has been assumed they have strong cognitive skills. 

Inuk hunter Gabriel Nirlungayuk he's hunted around polar bears since he was seven and has seen some complex hunting behaviours. He told ScienceNews this includes pretending to be asleep in open water to trick young seals to come closer.  

WHY DO POLAR BEARS NEED ICE TO SURVIVE?

Loss of ice due to climate change has a direct impact on the ability of polar bears to feed and survive.

The bears need platforms of ice to reach their prey of ringed and bearded seals. Some sea ice lies over more productive hunting areas than others.

Like other predators at the top of the food chain, polar bears have a low reproductive rate. One or two cubs are born in midwinter and stay with their mother for two years. 

Consequently, females breed only every three years. The bears don't reproduce until they are five or six years old.

From late fall until spring, mothers with new cubs den in snowdrifts on land or on pack ice. They emerge from their dens, with the new cubs, in the spring to hunt seals from floating sea ice.

Simply put, if there isn't enough sea ice, seals can't haul out on the ice, and polar bears can't continue to hunt. 

Football news:

Pochettino replaced Messi due to a bruised knee. Leo limped the next morning and did not train
Ter Stegen pro 1:1 with Granada: It's a shame, but a draw is a good result in such a game
Koeman pro 1:1 with Granada: Barcelona from the 2nd minute played against a team that was killing time
Ronaldo offered help to a player in Australia who was put into a coma after an attack
PSG, greetings from Balashikha. We placed your messages on billboards around the Parc des Princes field
Juventus is 10 points behind the leading Napoli after 4 rounds of Serie A
Tiago will not play for Liverpool with Norwich and Brentford due to a calf injury