Banff’s grizzly bear population appears to be relatively stable, but the survival rate of young bears is very low.
As part of the five-year, $1 million study by Parks Canada and Canadian Pacific Railway to look at ways to deal with an alarming number of grizzly bears deaths on the tracks, researchers looked at grizzly bear mortality and population trends.
Based on information from GPS tracking collars and remote cameras, Banff’s bear population is said to be relatively stable and in line with previous DNA-based estimates of about 50 to 70 bears. There’s an estimated 14 bears per 1,000 square kilometres.
Seven of 26 grizzly bears that were fitted with GPS collars for the study died between 2012 and 2014 – three natural deaths and four human-caused – but more animals such as bear 64 died when their collars weren’t working.
But Banff National Park wildlife ecologist Jesse Whittington said eight of 18 uncollared juvenile bears died before reaching the age of four, including two cubs struck by a train near Muleshoe in October 2012 – the last confirmed grizzly bear mortalities on the train tracks.
“Four young-of-year and four yearlings died. It’s probably pretty common with wildlife populations in general that really young animals have low survival rates,” Whittington said. “But the railroads do affect our juvenile survival rates.”
Two of those eight young bears belonged to grizzly bear 130, a wary female approximately 12 to 14 years old that’s had a tough time raising cubs in the busy and developed Bow Valley.
Whittington said 130’s story is an interesting one, noting she was fitted with a GPS collar near Banff in 2012 as part of the study, and then spent almost her entire summer that year in the backcountry with her two yearling cubs.
“Hardly anyone ever saw her and her two yearlings, but in the fall she wandered down from Johnston Valley and came down by Muleshoe,” he said.
“She hardly spent time on the tracks, but both her yearlings were killed on the tracks that night.”
The area there around Muleshoe and Five Mile has seen a high rate of bear mortality over the years and has been referred to as the “killing field.”
Bear 130 emerged from her den in spring 2015, once again with cubs in tow. By fall, she was spending time on the railway in almost the same spot by Muleshoe where her earlier offspring were killed on 2012.
Whittington said CP reported hitting the two cubs last October.
“We got a report of two young bears killed on the tracks,” he said. “We don’t know for sure and we can’t confirm her cubs were killed there, but it’s a high probability.”
Of the seven deaths of collared grizzly bears over the course of the study, four males died at the hands of humans, including male bear 144 who was destroyed by provincial wildlife officers when he killed sheep and llamas near Sundre.
Hunters killed an adult male bear, known as 125, in the Blaeberry River Valley in British Columbia when he wandered outside the protected national parks. Bears 128 and 148 were run over by vehicles in the parks.
In addition, three collared bears died naturally, including male bear 132, with only three per cent body fat, found dead in Johnston Valley. Female bears 72 and 133 also died of natural causes.
Grizzly bear 64, a former matriarch of the Bow Valley, is believed to have died of old age at 23. She’s not included in the mortality numbers because her collar had stopped working and she was never found.
“She was an older bear and she disappeared. She used to hang out in Banff and was probably one of our more famous bears. We’re pretty sure she died of old age, but we can’t totally confirm that,” said Whittington.
“It’s cool that we have had some bears dying of natural causes and these bears lived to be older ages, so we do have some females that are learning how to live in the Bow Valley, a very busy place, and surviving and living for a long time.”
Survival rates for adult female bears during this study were similar to those recorded by the Eastern Slopes Grizzly Bear Study from 1994-2002.
“They had really good female survival rates, around 95 per cent, and if you look at male bears, they had much lower survival rates than the females,” said Whittington.
“Males don’t matter as much as females. As long as you’re (bear) 122 and you have lots of females, you’re good.”
Through remote camera use, park researchers were also able to identify about 20 different family groups. The number of females with young ranged from four in 2012 to 10 in 2014.
“That’s kind of cool,” said Whittington. “If we do see over time that all of a sudden we don’t have as many family groups out on the landscape, that’s a warning bell that we might want to do some further investigation.”
They were also able to track the number of females with young-of-year cubs.
“Grizzly bears are pulse breeders. A bunch will have cubs in one year and then they might not for a while,” said Whittington.
“With last year’s really good berry crop, we’re hoping that 2017 is a pulse year where we see a lot of females with cubs.”
Whittington and other researchers developed a new statistical approach to estimate population density using information from radio collars and remote camera data, allowing them to look at trends over time and estimate grizzly bear density.
He said Banff’s density estimate of 14 grizzlies per 1,000 square kilometres is similar to scientist Mike Sawaya’s discovery during his DNA hair sampling project of grizzlies in 2006-2008.
“During that time he had roughly 15 bears per 1,000 square kilometres,” Whittington said. “So when I look at the camera and collar data, it’s about 14 bears square kilometres. To me, that’s encouraging and means this bear population is relatively stable.”
By comparison, population density is about 11 bears per 1,000 square kilometres between Hinton and Nordegg east of Jasper, while Jasper National Park’s estimate is 12 per square kilometre. Waterton is more in the range of 25 grizzly bears per 1,000 square kilometres.
“We’re right in the same ballpark as Jasper and have similar habitats,” said Whittington.
“But when you go down toward Waterton, areas like the Crowsnest Pass, that’s way more productive habitat and obviously you’d expect there’s a lot more bears down there.”
From 2010-2013, adult female mortality rates were at what scientists have deemed as an acceptable threshold of 1.2 per cent of the population. It then dropped below the threshold from 2014-2015.
“Continuing to work to keep bears on the landscape is really important right now,” said Whittington.
“We recently lost 72 and 64, who were matriarchs, and we’re going to have to work really hard to keep their offspring alive.”
