The daughter of a famous female grizzly bear has adopted one of her mother’s cubs in what is believed to be the first case of its kind in Kananaskis Country.
A 21-year-old grizzly bear emerged from the den in spring with three newborn cubs; however, it is believed a large male bear may have killed two of the cubs and the matriarch’s 13-year-old daughter took on the care of the surviving youngster.
Although rare, provincial wildlife experts say female grizzly bears will occasionally adopt and raise cubs that aren’t their own.
“This is the first occurrence where we’ve seen of an adoption of this sort in Kananaskis Country. It’s not to say it hasn’t happened before, but this is the first time we’ve observed it and recorded it,” said John Paczkowski, a biologist and human-wildlife coexistence team lead with Alberta Parks in K-Country.
“What I gleaned from reading the limited literature is typically these events occur after some sort of traumatic incidents, whether it’s an attack by another bear or another animal or some sort of severe incident that causes the cubs to separate.”
The 21-year-old matriarch of K-Country grizzly bears is referred to as No. 104 and her daughter is known as No. 139.
After emerging from the den, bear 104 was spotted with three cubs on June 5 but only two cubs by June 9. In the following days, she was observed multiple times with none.
Her offspring, No. 139, was initially seen with two cubs this year when she came out of her den.
“Then lo and behold, on June 12, [No.] 139 was observed with three cubs,” Paczkowski said. “We assume she adopted her mother’s cub.”
It is not clear why a grizzly bear would take on another bear’s cub, but Paczkowski said bear 139 seems to be treating her own two cubs and the adopted one equally.
“It’s not like one is ostracized or out of the group,” he said.
“She’s feeding them and travelling with them and they are all still together.”
Paczkowski said bear 104’s other two cubs likely perished, noting there had been several large male grizzly bears in the vicinity during the breeding season.
He said the strategy of males is to separate a female from her cubs – sometimes killing the cubs – so they can breed with the female. No. 104 may also have abandoned them so she could breed and they perished another way.
“In bears, the ovulation is induced so that the male has to be attentive and around a female for a period of time before she’ll be ready to breed or be receptive to breeding,” said Paczkowski.
“We see that happen where cubs and the female separate and then they reunite later after the breeding season, or sometimes that’s the push-off point where the cubs are now on their own.”
There are, however, other ways bears are separated from their cubs.
For instance, Paczkowski said No. 139 was swimming across a creek when she lost one of her cubs a few years ago.
“It got washed away, but a couple days later they were able to reunite,” he said.
Bear 104’s success rate of cub survival is extremely low, often kicking them out in their second year so she can breed again.
At the age of six in 2009, she had her first cub, losing it in the spring as most first-time mothers do. The next year she had another single cub, which was killed by another female grizzly bear when the two adult bears tussled.
The 21-year-old bear went on to have six other litters: in 2011, 2014, 2017, 2020, 2022 and 2024. Only a handful of her cubs have survived over the years.
Ryan Phinney, who is a former grizzly bear aversion technician for Alberta Parks in K-Country and specializes in bear behaviour, knows bear 104 and 139 well and hopes bear 139 has more luck raising cubs than her mother.
He said No. 139 got her first two cubs to dispersal age and both are still alive, but since then, she has had several failed litters, including losing all three cubs last spring.
“Taking on her mom’s cub might have been that motherly instinct kicking in, coming across an abandoned cub suffering, but that’s just me speculating,” he said.
In May 2011, Phinney was able to see No. 139 and her two siblings emerge from the den with their mother.
He was part of a capture team to collar 139 in July 2013 when she was two years old and weighed just 110 pounds.
“She was one of my favourite bears to interact and work with daily; she had such a personality to her, sassy but no aggression,” he said.
“In 2018 when she herself showed up with cubs, it was a really special moment. Since my involvement in bear management, she was the first bear I got to see as a cub-of-the-year to having cubs. To see it go full circle was amazing and it’s something I hold close to my heart.”
As for No. 139’s mother, Phinney said it was thought No. 104 had finally figured out how to avoid trouble for her cubs after her litter of three in 2017.
“Now that she’s 21 years old, she’s still searching for the answers,” he said.
“Hopefully 139 has better luck going forward. The fact that she still has all three, and the mating season is wrapping up, she’s positioned much better for success for this litter.”
Paczkowski has known No. 139 since she was a cub also, noting she has typical patterns of behaviour and movement.
As she was fitted with a GPS collar last September, he said staff can track her movements daily.
“That certainly makes it easy to monitor when she’s close at hand and when she’s not. When she’s out of sight, we can log in and see where she’s been moving,” he said.
It is suspected bear 139 will stick around the facility zone in Peter Lougheed Provincial Park for a while, but in the past she has made forays into the Elk Valley of British Columbia and travelled south to Highwood Pass and beyond.
“If the buffaloberry crop is good this year, she’s likely to stay where the berries are and feed on those,” Paczkowski said.
“Then towards the fall, she tends to move south and into the mountains and will resume digging roots and things like that.”
Bear 139 is characterized as very habituated, having learned to live in and around people and busy places.
“She grew up around people, has had thousands of encounters with people in the past, but has never shown any aggression or any real negative behaviour towards people,” Paczkowski said.
“I think that’s just because she’s so habituated and she just doesn’t freak out when people are around.”
Bear 139 is considered fairly road savvy, though she has been spotted walking down the middle of the road with her cubs in tow.
Paczkowski said the cubs are the “wild card.”
“They’re running to and fro and getting bolder, and making forays further away from their mother,” he said.
“They’ll pop out under a guardrail onto the highway, so it’s nice to have her away from the highway for now.”
If the mamma bear and her young ones are spotted, visitors are asked to give them plenty of space.
“Although she has been fairly tolerant of people over the years, the message is don’t crowd them,” Paczkowski said.
“They need this critical time to eat and put on food and especially now she is looking after three cubs, that’s a big job.”
The estimated population in the 4,200-square-kilometre Kananaskis Country is about 60 grizzly bears, based on a recent density estimate of 16 bears per 1,000 square kilometres, slightly up from the census in 2006 and 2008.
“That said, we have a quarter of the bears in our area that are moving back and forth between B.C. and Alberta and a lot of them are moving eastward,” Paczkowski said.
“We’re confident the bear population is stable to slightly increasing, and that we’re doing pretty well for our bear numbers in Kananaskis Country.”