Brown bear exfoliates using rock as a tool
The brown bear scrubbed its face using a barnacle-covered rock
A wild brown bear has been photographed using a barnacle-covered rock to exfoliate in the first recorded act of tool use by the species.
The observation was made in Glacier Bay National Park, Alaska by the University of Cumbria's Dr Volker Deecke.
The bear may have been using the rock to scratch irritated skin or remove food from its fur while moulting, Dr Deecke says.
It means brown bears could be more advanced than first thought, he says.
Dr Deecke's observations, which were made while on holiday in the park, have been published in the journal Animal Cognition.
Bears normally groom themselves when moulting by rubbing against trees or boulders or by using their claws, but have never been seen using tools before to scratch an itch.
Brown bears live quite solitary lives and it had been thought that species living like this were unlikely to generate that level of skill, says Dr Deecke, a senior lecturer at Cumbria University's Centre for Wildlife Conservation.
"These animals do have relatively large brains compared to their body size, the largest of any carnivore, and much larger than more social carnivores, like lions.
"There are a lot of ideas about sociality having impacted on brain size and cognitive abilities. It looks like bears are probably far more complex than we give them credit for," says Dr Deecke.
"From a cognitive perspective it's something quite sophisticated and requires certain brain processing powers that we didn't know bears had."
Dr Deecke says "humans are the ultimate tool users", but the finding makes bears the fifth non-primate mammal known to make use of tools.
Sea otters use rocks to smash the shells of sea urchins and clams, Asian elephants have been witnessed using tree branches to swat flies, some bottlenose dolphins use sponges to cover their rostrum while foraging and humpback whales have been known to make use of bubbles to help them trap groups of fish.
Although it is only a single observation, the discovery is an exciting prospect for researchers and could provide the basis for further research, Dr Deecke says.
"We don't know how common this behaviour is, but I think the real learning experience has been for me is how little we actually know about cognitive abilities of bears in general and brown bears specifically.
"All these experiments that have been done with primates looking at how complex their cognitive abilities are really haven't been done with bears" says Dr Deecke.
"I'm reasonably confident that we'll be in for a few surprises if and
when people do start paying more attention to bears and how they use their
big brains in the wild."