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Why are grizzlies dying on Canada’s railway tracks?


The Boss eats a moose carcass in Banff National Park.

Dan Rafla/Parks Canada

By Colette DerworizFeb. 8, 2017 , 11:15 AM

BANFF NATIONAL PARK, IN CANADA—Grizzly bear No. 122, a 270-kilogram male aptly nicknamed The Boss, spends a lot of time traveling and eating along the railway that winds through the Canadian Rockies here. Bears have used the tracks since Canada’s first national park was created in 1885, gorging on the buffaloberries that thrive along the right-of-way and the occasional carcass of an elk hit by a train.

Nearly 2 decades ago, the behavior turned risky, as trains began striking and killing grizzly bears. The Boss, father of at least five cubs and the biggest bear in the park, was himself struck in November 2010 but managed to survive. Many others weren’t so lucky, with at least
17 grizzlies killed by trains since 2000—a major hit to the local population of about 60.

“Why would that be?” wonders biologist Colleen Cassady St. Clair of the University of Alberta (UA) in Edmonton, Canada, as she walks along the tracks in a bright orange vest and fluorescent yellow helmet. “Why now? That’s the million-dollar question.”

She’s not the only one asking. In a brace of recent or forthcoming studies, scientists identify culprits ranging from blind curves to spilled grain, and propose steps for making the tracks safer worldwide.

Public outcry over the bear deaths spurred Cassady St. Clair and her colleagues to launch a study with officials in Banff National Park after the rail company provided CAD$1 million to start the project. Between 2012 and 2017, she and students and volunteers walked the railway and studied the tracks for clues. They examined the tracks’ curvature and topography; they tested scat to determine what bears were eating; they measured train noise; and they hung remote cameras from trees to record wildlife.

As part of the study, a team from Parks Canada captured and fitted 26 grizzly bears with GPS collars—including The Boss, 18 months after he was struck by the train. For 4 years the collars reported locations every 2 hours, yielding about 7500 bear locations. The data showed that only six grizzlies, including The Boss, regularly used the railway, perhaps because he deterred some other bears from using the rails.


In Canada’s Banff National Park, warning systems to alert bears to approaching trains might reduce deaths.

Getty Images/All Canada Photos

The team also evaluated the changing landscape of the past 20 years. For example, the Trans-Canada Highway expanded, bringing fencing and a system of wildlife underpasses and overpasses to allow animals to cross it. That changed the bears’ movements and cut down on the roadkill they scavenged, perhaps spurring them to scavenge more intensively on the tracks.

One stretch of track through an underpass for wildlife emerged as a hot spot: an S-shaped curve passing beneath Five Mile Bridge on the highway. At least seven grizzly bears have been hit by westbound trains speeding up on a straightaway that comes out of the curves, and a train crew reported hitting and likely killing an additional two cubs near here last October. “It turned out to be … a killing field,” Cassady St. Clair says.

Walk near Five Mile Bridge and you’ll get a hint why bears are dying: The curving tracks and topography tend to muffle trains’ whistles and rumbles. Steep slopes on either side might cause a bear to run straight on the tracks rather than down the hill.

At a second hot spot near the Trans-Canada Highway, known as Morant’s Curve, trains killed another three grizzlies. “If we’re right,” Cassady St. Clair says, “mitigating those two sites would have reduced mortality by half in the last 20 years. I find that very hopeful.”

Research by the UA team offers ways to make such spots safer. A paper being published this month in Animal Conservation considers the long-suspected culprit: spilled grain from trains carrying Canada’s wheat harvest. The study determined that trains spill 110 metric tons annually on the tracks in the national park—enough to feed 50 adult grizzlies for the year. Food spillage on tracks “is actually a very global issue,” says lead author and postdoc Aditya Gangadharan of UA. “Anthropogenic food leads to risk and can lead to mortalities for a number of species.”

That suggests it’s important for the railway to quickly repair leaking train cars, clean up spills, and limit trains from stopping in national parks. Some of these measures are already in place, though critics say the rail company hasn’t gone far enough.

Another study offers a way to warn bears of an oncoming train. In a paper in review at Ecological Engineering, Jonathan Backs, a Ph.D. candidate in engineering and biological sciences at UA, came up with an inexpensive device that can detect passing trains and relay a warning by radio. His device includes flashing lights and a dinging sound that alerts wildlife, giving them time to flee. Backs hopes it could be used on railways around the world.

Several other papers by Cassady St. Clair’s team, still in review or in process, suggest other strategies. They include new wildlife trails to provide escape routes, clearing vegetation along the railway, and fencing around hot spots.

As Cassady St. Clair says, no one step can stop all the track deaths. “There’s a lot more going on than grain,” she says. “Track considerations and topography, other aspects of human use, and a remarkable diversity of smaller factors combine—it’s a kind of perfect storm.”

In the meantime, The Boss will be out of hibernation soon and is expected back on the tracks, making some observers uneasy. But Cassady St. Clair expects that he’s a wiser bear now. “He has this firsthand experience. … He’s not going to mess with [trains] again.”

Source: Science Mag