Grizzly bears in Western Canada’s national parks are feasting on barley, lentils and canola that spill out from rail carriages — but it’s costing some of them their lives.
That’s because the bears’ opportunistic feeding habits are putting them at increased risk of getting hit by trains, according to a new study from the University of Alberta, published in the journal PLOS One.
At least 17 grizzlies have been struck and killed by trains in Banff alone since the year 2000, with some incidents involving more than one animal. Only a single grizzly was killed in the 15 years before that.
To investigate this unfortunate phenomenon, researchers fitted 21 bears in Banff and Yoho national parks with GPS collars to track their movements. They also analyzed 230 samples of grizzly bear poop collected over three years.
They found that 15 of the bears used the railway tracks occasionally, and four frequently.
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Three of the frequent visitors were young bears — dubbed “skinny teenagers” — that likely languished in the lower echelons of the grizzly hierarchy. These younger grizzlies were likely excluded from the best food habitats, and so were forced to supplement their diet with spilled grains, says the study’s co-author Colleen St. Clair.
Sure enough, scat collected from within 150 metres of the train tracks was far more likely to contain nutrient-rich grains, a clear indicator that bears in those areas foraged on spilled grains.
“It’s a dangerous place for a bear to be, and ultimately can cause them to be killed,” St. Clair says. “Like teenagers of all sorts, they live dangerously.”
It’s not just desperate “skinny teenagers” who frequent the tracks, however. One regular visitor is a dominant male nicknamed “The Boss,” the biggest bear in the park, who is attracted not so much by grains but by the presence of other animals, both living (such as elk calves) and rail-kill (mostly white-tailed deer).
St. Clair says most railway grain carriages were built before the boom in canola shipping rates, and weren’t designed to prevent the tiny canola seeds from leaking out. These seeds attract white-tailed deer in large numbers.
Bears can’t digest canola seeds, but they have no such problem with venison.
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The dominant adult bear’s movements also suggest that he “cruises up and down the rail, and we think he’s actually defending the rail and excluding other bears from it,” St. Clair says, adding that this particular bear appears to be “really good at avoiding trains” — likely because he was struck by one himself in the past, and is wiser for it.
But while this alpha bear has successfully learned to use the rail to his advantage, most grizzlies aren’t as lucky. Many move along the railway tracks because it’s their only means of avoiding human-populated areas, St. Clair says.
“The way that bears specialize in rail use are really surprisingly different. It’s not for the same reason and not with the same strategy.”
As far as possible solutions are concerned, CP Rail has been working with the federal government to replace and repair grain carriages to reduce spillage, St. Clair says.
She and her team have also invented a special warning device that could be used in high-risk, frequently visited sections of track to alert bears to oncoming traffic.
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St. Clair says the bears’ plight has captured Canadians’ hearts and minds.
“People just find it awful that this heritage form of transportation would kill grizzly bears in Canada’s first national park,” she says. “In a way, it’s a cultural problem as much as it is a biological problem.”
But grizzlies aren’t the only animals on St. Clair’s mind. She hopes this research could help inform interventions to help other species that get hit by trains in other parts of the world, such as elephants in India, gazelles in China and brown bears in Eastern Europe.
“We can offer some new ideas that might be applied to all those places around the world where there is an awareness but there isn’t funding to do anything about it,” she says.