There is, thankfully, increasing recognition that traditional cultures with vast and deeply rooted firsthand experience observing animals – and participating intimately in the same ecological webs as them – may (surprise, surprise) have insights into those species that Western science remains oblivious to, or has only just begun to document.

A recent review in Arctic suggests that Inuit historical reports and traditional ecological knowledge (TEK) many Western commentators and scientists dismissed as folklore are more likely accurate references to a rare predatory method polar bears may, very occasionally, employ.

The method? Oh, just bashing in the heads of walruses with hurled or slammed chunks of ice or rocks – that’s all.

This engraving, taken from Charles Francis Hall's 1865 book Arctic researches, and life among the Esquimaux, depicts a polar bear throwing a rock at a walrus. (Smithsonian Libraries/Public Domain)

Despite frequent oafish depictions in popular culture, the walrus is, all things considered, a pretty darn formidable beast. It’s the second-biggest pinniped after the northern and southern elephant seals – bulls may weigh a ton or two – and the most extravagantly toothed. It’s not just the heft and the sharp tusks: It’s also the impressively tough hide, thick skin, and a super-solid skull.

Polar bears do sometimes hunt walruses, but the typical target is not one of the heavyweight, sabred adults but a calf. As the authors of the Arctic paper note, though, a young walrus is still tough to quickly dispatch, as “even small walruses have large, heavily constructed skulls so that in most cases, even killing a calf would require multiple bites and probably blows to the head with the front paws, as a polar bear’s bite is not capable of crushing the skull and brain.”

(Some evidence suggests polar bears may intentionally provoke hauled-out walrus herds to stampede into the water, in the hopes that – as sometimes happens amid the pell-mell and tonnage of all those galumphing pinnipeds – calves are trampled to death.)

Polar bears do sometimes hunt walruses, but the typical target is not one of the heavyweight adults. Image © Caterina Sanders

Written by three experienced polar-bear researchers, Ian Stirling, Kristin Laidre, and Erik Born, the new report notes that Native accounts of polar bears employing tools to try to kill walruses have been recorded from the North American Arctic – primarily western Greenland and the eastern Canadian Arctic, but also Alaska – since the late 1700s.

A well-known 1865 engraving, for example, shows a bear lofting a rock from a cliff at a resting walrus – an illustration based on information from the American explorer Charles Francis Hall’s Inuk guide from Baffin Island (see illustration above).

More commonly, in these accounts, the hunting bear uses not a rock but a chunk of ice to bludgeon a walrus. For instance, the paper quotes the British explorer George Francis Lyon in 1824, describing an observation shared with him by a man named Ooyarra in Foxe Basin, Nunavut: “On one occasion, [Ooyarra] saw a bear swim cautiously to a large piece of rough ice, on which two female walruses were lying asleep with their cubs. The wily animal crept up some hummocks behind this party, and with his forefeet loosened a large block of ice; this, with the help of his nose and paws, he rolled and carried until immediately over the heads of the sleepers, when he let it fall on one of the old animals, which was instantly killed. The other walrus with its cub rolled into the water, but the young one of the stricken female remained by its dam; on this helpless creature the bear now leaped down, and thus completed the destruction of two animals which it would not have ventured to attack openly.”

The accounts the Arctic paper mentions aren’t only historical: They include insights from a Greenlandic Inuk hunter who, in the late 1990s, found a just-killed walrus alongside fresh polar-bear sign, and, from his analysis of the scene, concluded the bear had attacked the pinniped with a hunk of sea ice it had specially smoothed. That same sort of deliberate manipulation of a piece of ice to make a killing weapon was also mentioned during a 2020 interview with an Inuk at Arctic Bay, Nunavut (part of a separate study).

Along with these first- and secondhand reports from Inuit observers concerning wild polar bears, the authors of the paper considered published accounts of tool use in captive bears. In captivity, brown bears – the immediate ancestor and closest relative of the polar bear – have moved logs and other objects directly beneath suspended food and stood atop them to reach the prize.

Even more relevant to the subject at hand, a rather spunky captive polar bear in Japan named GoGo has been documented using tools to obtain meat hung high above his pool at Osaka’s Tennoji Zoo. Having previously tossed a piece of pipe or brandished a length of wood to knock the meat down, GoGo now apparently prefers throwing a buoy-like object he propels with both forepaws, “much like shooting a basketball.”

There’s also intriguing collar-cam footage captured by the U.S. Geological Survey during research in Alaska, showing a polar bear nosing a chunk of ice along and flinging it into the water:

In a Science News article by Gloria Dickie, Stirling suggested this ice-flinging may have been connected with the bear’s hunting of a seal.

Bears in general have long been reckoned quite intelligent by human standards. The manipulation of objects by captive brown and polar bears to secure something tasty suggests that, as the authors write, “an occasional adult polar bear might be capable of mentally conceptualizing a similar use of a piece of ice or stone as a tool to attack the well-protected brain of a walrus in order to kill it.”

Polar bears killing walruses with blocks of ice – maybe smoothed into balls ahead of time – puts them in select company with other non-human animals known to use tools, from chimpanzees and dolphins to crows and octopuses.

The authors of the Arctic paper stress the similarity but also the rarity of Inuit accounts, historical and contemporary, describing this kind of weapon-wielding by polar bears. “The small number of reports suggests to us that the use by polar bears of tools to kill walruses is an unusual event,” they write. Such accounts aren’t, according to the paper, known from other areas of combined polar bear and walrus range, such as the Russian Arctic or Norway’s Svalbard Archipelago.

Yet the special challenge represented by walrus as a potential prey item – as compared to more easily killed seals, for example – might encourage the odd, creative polar bear to go the extraordinary length of employing an object to attack it with. Given bear cubs learn the ropes from their mothers, perhaps it’s a technique passed down from one generation to the next in particular regions.

The new paper also shines more spotlight on the immense value of TEK for scientific understanding of wildlife behaviour and other ecological phenomena. Speaking to Live Science, Stirling said, “I have always been impressed with the accuracy and reliability of animals reported by experienced Inuit hunters, so I thought it was likely the accounts might not just be myths but the result of actual observations, even though the behavior itself is likely quite rare.”

Finally, we’d be remiss not bringing climate change into the discussion: One of many concerns about the drastic reductions in Arctic sea ice underway because of warming temperatures is increased reliance by walruses on land-based rather than offshore haul-out sites, which may increase predation risk from polar bears (and trampling risk to calves, to boot).

Header image © Hans-Jurgen Mager