Climate change may be driving more aggressive polar bears towards areas where people live, and the consequences could be lethal.
“You’ve got this perfect storm set up where you’ve got bears that are spending increasing amounts of time on land becoming nutritionally stressed, moving into areas of human settlements,” says Todd Atwood, a wildlife biologist at the US Geological Survey. This makes the bears more likely to come into conflict with humans.
Atwood was a member of a team that combed through nearly 150 years of records of bear attacks in Canada, Greenland, Russia, the US and Norway. They drew their data from government agencies, news reports and, in the older cases, from ships’ logs.
Between 1870 and 2014, they found 73 cases of polar bears attacking a group of people or an individual, with 63 people injured and 20 people dead. Bears were acting in a predatory manner in most attacks, and it was male bears that were more often involved.
Where details were available, the researchers assigned the attacking bear a score reflecting its body condition. It turned out that 61 per cent of these bears were in “below average” condition – a situation Atwood says is down to them not finding as much food because of dwindling time on sea ice, their habitual seal hunting ground.
Polar bear attacks averaged around eight or nine per decade, Atwood says, but from 2010 to 2014 alone there were 15. “That does lead you to hypothesise that around 2000 we might have hit a shift in the kind of conditions in the Arctic.”
Robert Rockwell at the American Museum of Natural History in New York says that the study is a step in the right direction. “It’s a good move because we are going to have increasing encounters with bears. Some of it is due to climate change – more bears are going to come on to shore,” he says.
While he agrees that bears in suboptimal condition are feistier, he disputes the idea that bears moving on to land will always be starving. Instead, he argues that they could in some cases be supplementing their diets by exploiting goose eggs, caribou and other foods.
Yet another issue could be at play. Rockwell says that with more tourists going on polar bear tours, the animals are becoming more used to humans. During his work on the western side of Hudson Bay, he has noticed that the bears have become harder to deter. “They’re becoming habituated to noise, they’re becoming habituated to people,” he says.
All things are relative in the world of bears, though. Atwood’s paper cites another study that found 63 cases of black bears causing deaths from 1900 to 2009 in North America alone. “It would appear that polar bear attacks are relatively rare when you compare them to brown bear and black bear attacks,” he says.
How to survive a polar bear attack
In examining historical records of polar bear attacks, Todd Atwood at the US Geological Survey and his colleagues have uncovered some clues as to how best to ward off a bear once it has attacked. Successful defences have included using a cellphone light, the arrival of a loyal dog, having someone fly a helicopter over it and even poking a bear in the eye. In nine cases, though, the bear left of its own accord.