BANFF – Bears are feeding on contaminated grain and vegetation along the railway line in Banff and Yoho national parks.
Researcher Sonya Pollock set out to determine if grain spilled from hopper cars, as well as vegetation eaten by grizzly bears growing next to the train tracks, could expose bears to pollutants that are usually found within a transportation corridor.
Measuring several heavy metals and polyaromatic hydrocarbons (PAHs), she found grain was much more contaminated than dandelions, especially for the metals molybdenum, iron, lead, and cadmium and for heavy, carcinogenic PAHs.
“Lead concentrations in it were about three times higher than the federal limits established for animal feed,” said Colleen Cassady St. Clair, a professor of biological sciences at the University of Alberta, who was Pollock’s supervisor.
Pollock also measured metals in bear hair, expecting that the bears that made the greatest use of the transportation corridor, which includes the Canadian Pacific Railway line and the Trans-Canada Highway, would have higher concentrations.
“Surprisingly, they did not,” said Cassady St. Clair. “But male bears had higher concentrations of metals than females.”
The research also showed a link, albeit weaker, between metals and both elevation and use of ski hills.
“These patterns were driven by just a couple of bears, but sources of metal contamination on ski hills might merit additional exploration,” Cassady St. Clair said.
Pollock said she studied when grizzly bears most often travelled along the train tracks, which was highest in spring and fall.
“Spring railway use may be correlated with early herbaceous feeding opportunities, and use in the fall with fruit availability along the railway or the higher deposition of train-spilled grain due to higher export volumes,” said Pollock.
This paper, recently published in the Environmental Management journal, came out of a five-year Parks Canada-Canadian Pacific Railway study to look at the reasons for an alarming number of grizzly bear deaths on the train tracks in Banff and Yoho national parks. The study wrapped up in 2017.
At least 17 grizzly bears, which are a threatened species in Alberta, were killed by trains in the two parks between 2000-13, striking a blow to the local population of about 60 grizzlies. These mortality numbers do not take into account bears that may have been struck by a train but never found.
The CP-Parks Canada study indicated approximately 110 tonnes of grain is spilled or trickled from trains across a 137-kilometre stretch of railway in Banff and Yoho – enough to feed 50 bears for an entire year.
A spokesperson for Canadian Pacific Railway, Salem Woodrow, said it is important to note that there has been no confirmed grizzly strikes or deaths on the railway line in Banff or Yoho national parks since 2013.
She said CP thanks all of the researchers who have significantly advanced the knowledge of how wildlife and the railway environment interact in the past decade.
“As the company approaches the end of a multi-year vegetation management program throughout Banff and Yoho national parks, CP will continue to focus on science-based mitigations to prevent wildlife mortality on the railway,” said Woodrow.
Railway transportation is a major producer of both heavy metals and PAHs, which originate from incomplete fossil fuel combustion, material abrasion, machine grease and oils, and creosote-treated railway ties. These can accumulate in the surrounding soil and vegetation.
In addition, researchers observed contaminated areas along the railway such as grease lubricating stations, which occasionally contained grain-filled bear scats, and also heard reports of bears with oil on their fur.
Other studies suggest exposure to even low concentrations of some pollutants can jeopardize the health of wildlife.
These include changes in behaviour, growth, metabolism, or reproduction such as reduced sperm concentration and mobility. Exposure to PAHs, especially in-utero, can cause developmental problems.
“Exposure to both heavy metals and PAHs can reduce the condition and fitness of individuals, with the potential for population-level effects,” said Pollock.
“Railway-associated contaminants from any source may require mitigation when they occur in protected areas and involve threatened population.”
As Pollock expected, male bears in the study area had higher overall metal concentrations in their fur than female bears.
“This may have occurred because female bears are able to transfer contaminants to their offspring via milk or because male bears have much larger home ranges with greater cumulative exposure to metal pollution,” she said.
“Further, male bears spend less time hibernating than female bears and their comparatively larger body mass increases nutritional demand, both factors potentially heightening exposure.”
Higher rates of scavenging and predation by male bears would provide additional exposure via bioaccumulation, said Pollock.
“However, we found no evidence that metals accumulated with age in bears as reported in other studies,” she said.
Pollock ’s first recommendation to reduce wildlife exposure to contaminants on the railway line is the speedy removal of grains, such as wheat, barley, canola, flax, lentils, peas and soybean.
“Grain removal might be focused in areas like railway sidings where trains are stopped for extended periods and can accumulate both grain and pollutants,” she said.
“Lubricating stations along railways should be fenced or cleaned to limit exposure of wildlife to petrochemicals that contain numerous toxicants, including metals and PAHs.”
Pollock said the study’s result linking metal and ski hill use by bears also warrants further investigation.
This was largely driven by one adult female bear, which had consistently high metal concentrations in her hair and spent a large proportion of her time on a ski hill. There was also a sub-adult male bear that regularly used the ski hill, but to a lesser extent.
Pollock said more work is needed to know if vegetation could harbour metals associated with fertilizers and chemical additives for snow hardening, herbicide application, snowmaking operations, including pumping systems, alloy pipes, and potentially contaminated water sources, and general machinery operations such as grooming and clearing.
“Although the association between metals and use of ski hills in our data was caused by just two individuals, more work on metal exposure in ski hill ecosystems could be warranted because bears consistently use ski hills and attract considerable tourism,” she said.
Studies have shown this population of grizzly bears has some of the lowest densities and reproductive rates in North America.
“This may increase its vulnerability to the detrimental effects of railway-associated contaminants,” said Pollock.