An adult female grizzly bear has been killed on the train tracks near Lake Louise, orphaning two yearling cubs, and striking a blow to local the grizzly bear population.
The death of the female grizzly is not an automatic death sentence for the orphaned cubs, but wildlife experts suggest their chances of survival are not good.
Officials say the death of female bears – the so-called reproductive engines – has implications for the population, estimated to be about 60 individuals in Banff National Park.
“We’re not dealing with a big population. This is a huge blow to the Lake Louise area and a huge blow to the population,” said Hal Morrison, human-wildlife conflict specialist for Lake Louise, Yoho and Kootenay.
“She was a really healthy, beautiful adult female in the prime of her life.”
The grizzly sow was killed on the Canadian Pacific Railway line about three kilometres east of Lake Louise on the night of May 28, and park staff spotted two second-year cubs near the scene the following day.
The cubs’ chances for survival are not considered to be good.
Research with the Eastern Slopes Grizzly Bear Project revealed cubs in this region, on average, typically stay with their mothers for about four years.
“It’s too tough to tell for sure, but they’re not good when we look at the survival rates,” said Morrison.
The cubs are thought to weigh about 50 pounds and officials say one of the biggest threats is protection from other bears or even a group of coyotes.
“The cubs are a year old and they look smallish, but they are certainly able to forage for themselves and we’ve seen them foraging well,” said Morrison. “What really is not so great for them is they will now lack their mother’s protection.”
Parks crews have no plans to capture and fit the young bears with ear tags, as they want to avoid putting any extra stress on them at this time.
Staff are keeping a close eye on the young bruins and gently shepherding them away from the train tracks and Bow Valley Parkway whenever possible.
Morrison said they might even try drawing the cubs away from those areas with a scent trail; for example, using meat or perhaps even their mother’s hide.
“We’ve chosen not to try and capture them because it comes with a fair bit of a risk and it’s stressful for them. They’re little guys,” he said.
“We also don’t want to run the risk during capture of splitting up the siblings. They obviously have a better chance of survival if they’re together and they can support each other.”
This is the second grizzly bear death in Lake Louise in a three-week period. A 415-pound male grizzly was hit and killed on the Trans-Canada Highway in the middle of the night of May 9-10.
In the current case, Parks Canada says no grain was found at the scene of the incident, nor was there any grain detected in the bear’s stomach following a necropsy.
That said, grizzly bears are known to be habituated to the train tracks throughout the national parks, where they have come to realize they can get a quick and easy meal.
The death of this female grizzly is reminiscent of the death of famed bear No. 56, a small bear collared as part of the Eastern Slopes Grizzly Bear Project, which was hit and killed by a train in 2001.
Her death near Lake Louise was particularly significant because she, too, had two young cubs and she was heading into her prime age as a breeding female.
Number 56’s two cubs, which were cubs of the year and weighed about 95 pounds when they were orphaned, survived that year and managed to enjoy a bumper berry crop season before denning.
The next summer one of the cubs was killed on the highway. The surviving cub denned again the following winter, but was killed by a male bear when two years old.
Morrison said extensive monitoring last year determined three sows in the Lake Louise area had produced cubs – two females with two cubs each and one sow with one cub.
He said the grizzly that died on the weekend was untagged and park crews suspect she is the same grizzly that spent a chunk of last year at the Lake Louise ski hill with her then-newborn cubs.
“We don’t know a lot about her,” said Morrison.
Park officials say the death of this female grizzly does not yet put Banff over the scientifically calculated and acceptable mortality threshold for females.
They say two of three grizzly bear mortalities in 2007 were females. In 2008 and 2009 there were no female grizzly bear deaths, but in 2010 there was one and now there is another this year.
“We are actually still below the threshold; however, the loss of any female grizzly bear has negative implications for the population’s persistence,” said Kris McCleary, Parks Canada’s science advisor for the mountain national parks.
Meanwhile, trains continue to be the single biggest killer of grizzly bears in the mountain national parks, accountable for a third of the human-caused deaths.
According to a recent Parks Canada report, there were 64 known grizzly bear mortalities in the mountain parks of Banff, Jasper, Kootenay, Yoho, Waterton, Mount Revelstoke and Glacier between 1990 and 2009.
Of the 64 deaths, 49 were caused by humans and more than half were female bears. The Lake Louise area alone accounted for 12 of the human-caused mortalities.
Parks Canada officials say they have been working with Canadian Pacific Railway to address the problem on the tracks, pointing to a $1 million research plan to mitigate rail-related grizzly bear mortality in Banff.
Research has been looking at vegetation management, whistle zones, and reviewing opportunities for wildlife fencing and culverts in high-risk areas.
Through the new five-year research program, other experiments may be used in a bid to dissuade grizzly bears from searching for grain on the tracks.
McCleary said they’ve worked hard over the winter to develop a joint research plan, including work with experts across North America to figure out the best mitigations to reduce railway mortality.
“We have spent a lot of time investigating which mitigations have proven unsuccessful, and then looking further into mitigations that show promise,” she said.
“I can’t really speak about those yet, but we’ll be unveiling the research plan in the next couple of weeks.”