It’s a lesson young grizzly bear cubs in remote wilderness areas don’t have to learn – how to cross a deadly stretch of highway smack dab in the middle of their home range.
But a high-profile female grizzly, known as number 64, has been teaching her three young-of-year cubs how to use two overpasses to get them safely across the busy Trans-Canada Highway in the Bow Valley.
“This is nothing unexpected from her as she’s certainly one of the heaviest users of the overpasses,” said Steve Michel, a Parks Canada human-wildlife conflict specialist.
“She took her previous cubs across there, too, so it’s certainly not unusual or unexpected for her to be showing this year’s cubs the same thing.”
Bear 64 was recorded using both the Redearth and Wolverine overpasses three times in early August – on Aug. 7, 9 and 10 – but the cubs were only visible in an Aug. 10 photograph.
Michel said he suspects the three cubs were there on the other two occasions as well, but likely behind the camera and not caught in the footage.
“There’s definitely no evidence she was crossing prior to then, which makes sense as she started to range further in early August in search of good berry crops,” he said.
Ironically, two female cubs from a previous litter of bear 64 have been killed along the transportation corridor. Bear 109 was killed on the train tracks last year and bear 108 died on the highway mid-July.
One other unmarked female grizzly bear has also been using the underpasses and overpasses regularly to go back and forth across the Bow Valley since early June.
She has two cubs in tow.
“We’ve certainly been aware of her and seen her around for the last couple of years,” said Michel. “She’s a younger female, but she’s been using the crossing structures quite a bit.”
The busy Trans-Canada Highway cuts east-west across the Bow Valley in Banff National Park, making it difficult for wildlife to travel north-south through the Rocky Mountains.
In the summer months, this stretch of highway reportedly sees more than 25,000 vehicles per day, translating to one vehicle every two to three seconds.
To help animals navigate the highway, there are two overpasses and 22 underpasses from the park’s east gate to Castle Mountain. From there to the B.C. border, there are currently four overpasses and nine underpasses, with more on the way.
Since the mid-1990s, there have been 198,811 crossings by wildlife in total, including 182,106 ungulate crossings, 5,547 wolf crossings and 1,493 cougar crossings.
There were 1,317 black bear crossings and 873 grizzly bear crossings, but until now, researchers had no idea how many individual bears those numbers actually represented.
But the results of a DNA study showed 11 individual grizzlies (six males, five females) used the structures in 2006, 12 (six of each sex) used them in 2007 and 10 (five males, five females) in 2008.
The DNA study concluded just a few individuals are responsible for the bulk of the use. Researchers also cautioned these are raw numbers and not a population estimate.
As for bear 64, Michel said she has been covering quite a bit of ground this summer, including the Bow Valley. There have been no public sightings of her on the north side of the Bow Valley, though.
“She did go all the way up the Spray and Goat Creek, and showed up on provincial lands for a day or two. She’s also been up as far as Egypt Lake, and all through Healy Pass and along the Sunshine Road,” he said.
“She’s doing well and all three cubs are still with her.”