The number of mammals killed by trains in Canada’s Rocky Mountains could be reduced if mitigation targeted places where four things co-occur: higher train speed, track curvature and the presence of water bodies that are close to the railway. These factors were identified by University of Alberta researchers who used 24 years of wildlife mortality records to pinpoint the most dangerous locations.
In collaboration with biologists from Parks Canada, Faculty of Science professor Colleen Cassady St. Clair and her team in the Department of Biological Sciences used the mortality records of 646 animal strikes reported by CP railway from 1995 to 2018 in Banff and Yoho National Parks.
Her previous train-strike investigations focused on grizzly bears, which account for less than one per year over that same 24-year time period.
“We wanted to know if we could leverage the statistical power of all these collisions with other species to identify the characteristics of locations with the most strikes overall. From that information, we hoped to suggest mitigation strategies that might make those locations less dangerous,” said St. Clair.
All told, there were 11 species in the study broken into three groups: 59 bears, both black and grizzly; other carnivores that included 27 wolves, cougars, lynx and coyotes; and a category for ungulates made up of 560 moose, elk, sheep and deer—both whitetail and mule.
Train speed, blind spots and nearby water heighten risk
The data showed that the top characteristic of places with higher animal mortality was train speed, followed by proximity to water from the track, amount of water nearby, and track curvature.
“Both are sites where trains are travelling at a relatively higher speed, the track is curved, they're adjacent to water and, especially for the most important location near the Banff townsite, there's a lot of water.”
“We think that train speed and track curvature impede an animal's ability to detect trains, while the presence of nearby water prevents them from getting off the tracks quickly,” said St. Clair.
She noted that these four characteristics also describe two locations that account for half of the area’s grizzly bear strikes—just west of the Banff townsite and just east of the Lake Louise townsite..
“Both are sites where trains are travelling at a relatively higher speed, the track is curved, they're adjacent to water and, especially for the most important location near the Banff townsite, there's a lot of water.”
St. Clair added bears' mortality from train strikes peaks in late June, the time of year when water levels are the highest and the animals may benefit more from using the tracks as a travel corridor.
“We've had a hunch about these limitations to train detection and animal movement for some years, and the mitigation for these kinds of sites is already underway,” she said.
Parks Canada has been clearing wildlife trails near sites where past bear mortality occurred as part of a pilot project to see whether making it easier for animals to get off the tracks cuts mortality. The railway has cleared vegetation to increase sight lines for oncoming trains. St. Clair’s team has also developed a wildlife warning system.
Finding middle ground on speed limits
Unfortunately, slowing train speed is not generally popular with railways as St. Clair said speed is arguably the railway’s most important determinant of profit margin.
“There's tremendous resistance to reducing train speed across the board, but it might be possible to reduce it in specific places where there is high risk for wildlife collisions.”
Specifically, St. Clair speculates that “if the speed limit change were moved by just four kilometres farther away from the townsites, where trains slow anyway for human safety, it would have covered those two hotspots of grizzly bear mortality,” she said.
She noted that, as with the rising waters in June, there are specific times of the year a seasonal speed-limit reduction of trains could be effective at reducing wildlife mortality for some species at this and other locations. For instance, four train collisions killed more than 100 pronghorn antelope between last Nov. 9 and Nov. 20 in Saskatchewan.
St. Clair explained the best mitigation for highways has been to put up a barrier fence and perforate it with crossing structures, but that’s not affordable for railways where there's not a risk of human deaths.
“Bear strikes receive extra attention because bears have such low population densities, but many species around the world are affected by train strikes and there is a large and growing need for more information about how to mitigate that problem.”