Tool use is considered a marker of intelligence within the animal kingdom, and since polar bears (Ursus maritimus) sit within the Ursidae family, a group of mammals considered to exhibit elaborate hunting strategies, it’s not beyond the realms of possibility that they too might know how to turn their paw to a tool. Despite this, historic accounts from Inuit hunters of polar bears using rocks and icy boulders as a means of taking down walruses were largely ignored by early explorers and scientists. Now, a new study has reviewed historic and contemporary accounts of bears and balls with observations of captive animals to conclude that yes, actually, there probably are polar bears bonking walruses over the head with giant blocks of ice.

“It’s been my general observation that if an experienced Inuit hunter tells you that he’s seen something, it’s worth listening to and very likely to be correct,” polar bear biologist Ian Stirling, first author on the new paper published in the journal Arctic, told Science News. Stirling believes that while the academic literature isn’t quite there yet, there's plenty that tips in polar bears' favor as a brighter breed of hunter. “We don’t know anything experimental or objective at all. However, we have a great deal of observational information that tends to suggest polar bears are really smart.”

According to the paper, there have been several reports of polar bears using ice and rocks to kill walruses (Odobenus rosmarus) dating as far back as the 1700s from Greenland and the eastern Canadian Arctic. They do note however that these accounts, while consistent, are perhaps contradicted by the total lack of similar reports in other parts of the world where there are plenty of walruses to be bludgeoned to death by boulder-wielding polar bears. The researchers, therefore, wanted to try and corroborate the accounts using more modern examples. By painting a clearer picture temporally as well as geographically, they hoped to better ascertain if tool use is within the grasps of the species as a whole, or if the polar bears of Greenland and the Canadian Arctic are just uniquely mean to walruses.

To do this, they reviewed contemporary accounts including an interview with an Inuk hunter recorded by the team in 2011. The hunter had found fresh tracks that appeared to show a bear had shifted some salty berg ice and smoothed its edges before sitting in wait next to a breathing hole. When a walrus had surfaced, the hunter said the bear caved in its skull with the ice (evidenced by its very broken face) before dragging it out of the water to eat. In a separate interview another hunter told Born et al of a ball made by a mother for its cubs. “If mathematicians had measured it, they would be amazed at how perfectly round it was,” they said.

"The historic account that I found most interesting was that of Knud Rasmussen because he was a very expert arctic explorer and anthropologist," said Stirling to IFLScience. "He also spoke Inuktitut so there would be no errors or misunderstandings resulting from translation. That observation seemed very reliable and then the one from Greenland in the 1990s where the hunter came across where it appeared a walrus had been killed by a bear just a few minutes before."

Since the paper’s publication, Stirling was sent the video above by US Geological Survey scientist Anthony Pagano that appears to show a female polar bear playing ice hockey before hurling the homemade puck at a seal’s head. Rude, but impressive.

Finally, the paper looked at accounts from captivity of both polar bears and their closest relatives, brown bears. One example included Tennoji Zoo, Osaka, where in the 1990s keepers crafted some enrichment for a polar bear named GoGo in the form of meat suspended beyond his reach. The bear independently refined a technique of using toys as tools including piping, logs, and a ball by throwing them like a basketball to knock the meat down. A similar approach was seen among captive brown bears during an experiment by Waroff et al., in 2017 as they learned to hurl unfamiliar objects as a means of obtaining food.

“Taken together, these observations, along with GoGo’s ability to access a bait suspended out of his reach by coordinating the use of both front paws to throw a tool accurately and thus determine its trajectory, leave us to speculate that an occasional adult polar bear might be capable of mentally conceptualizing a similar use of a piece of ice or a stone as a tool to attack the well-protected brain of a walrus in order to kill it,” concluded the study authors. “The long history of similar observations reported from the wild by Inuit hunters, when combined with the observations of captive polar and brown bears, suggests the former may also have the ability to conceptualize the possible use of tools in the wild.”

[H/T: Science News]