BANFF – Banff’s reintroduced bison herd has had at least 10 more calves this spring.
The birth of the 10 “little reds,” as they are affectionately nicknamed for their red fur, brings the herd size to 45.
Parks Canada officials say the new additions to the herd, which will start to turn more of a chocolate brown colour like their parents in the coming months, appear to be healthy.
“We started with 16, so the the population has almost tripled, which is pretty neat,” said Karsten Heuer, project manager for the $6.4 million bison reintroduction project in Banff National Park.
“We know that at least one of those 10 babies is the calf of a new mother and that new mother was herself born in the first crop of calves in 2017 – so we have the first true made-in-Banff bison mom.”
As a wild species absent from the park for 160-years, Parks Canada translocated 16 plains bison from a disease free herd in Elk Island National Park to a 16-hectare soft-release fenced pasture in the Panther River Valley on Feb.1, 2017.
The 10 pregnant females in that herd gave birth to 10 healthy calves – seven females and three males – that spring in the fenced pasture, which was an attempt to anchor them to their new home before releasing them into a larger area.
“The original 10 cows that we brought in from Elk Island were already pregnant from other bulls in the larger Elk Island herd,” said Heuer. “That was really important from a genetic standpoint.”
In spring 2018, the original 10 female bison from Elk Island National Park gave birth to more calves inside the fenced pasture.
After spending 16 months in the fenced pasture, a herd of 31 bison was released into the larger 1,200-sq.-km reintroduction zone on July 29, 2018, marking the beginning of the free-roaming phase of the project.
The following summer, in 2019, only three calves were born.
Heuer said the herd appears to have returned to more normal calving patterns this year, including higher calving rates.
“Over the past couple of years they’ve been a little bit out of a normal rhythm in that they’ve been calving throughout the summer and even into the fall, and that’s been happening since we released them," said Heuer.
“We think that was because of the chaos and the learning and the lack of the right bulls hooking up with the right cows during that sort of chaos of being released into a huge 1,200-sq.-km area,” he added.
“We were really hoping that they would get back on the regular schedule and it seems that they have. They have at least 10 calves to date in the month of May and that’s right when bison normally calve, so that’s really nice and affirming.”
The new calves appear to be healthy, especially having survived a harsh winter with lots of snow.
“They are actually doing as well as how they did in captivity,” said Heuer, noting the herd was monitored through a spotting scope.
“They really seem to be honing in on what’s useful to them and learning quite quickly how to make a go of it and stay healthy.”
With a later start to spring this year, the bison reintroduction team did have some concerns, though.
“I was a little worried that they would be motivated to go east and maybe even leave the reintroduction zone to find greener grass, but that didn’t happen,” said Heuer.
“I think why it didn’t happen is because they just have a better detailed knowledge of the area that’s available to them.”
In that sense, Heuer compared the bison to other wildlife.
“Like a grizzly bear knows over many years and even generations where berries are ripening at different times of the year within its home range, I think these bison are starting to do that,” he said.
“They’re real survivors and they’re really succeeding in making it work in this area that’s available to them.”
Heuer believes all 10 bison calves have a good shot at surviving these early stages of life in the wild.
“Maybe even their chances of survival are higher early on in this reintroduction project than they might be later on, as potential predators like grizzly bears and wolves maybe learn to exploit them,” he said.
“From everything we’ve been seeing so far, grizzly bears and wolves haven’t quite figured out how to take advantage of this new potential prey source.”
That said, there have been some interesting observations between bison and wolves caught on remote cameras in the area.
“You’ll see the bison come by, and then within a few minutes a couple of wolves come past, and then a few minutes later the wolves turn around and a teenage male bison is actually following the wolves, and it’s smelling the places where they urinated and where they stopped,” said Heuer.
“It’s not your typical predator-prey interactions that you might expect. It’s almost like a mutual curiosity of these long-term ecological dance partners … they’re really sort of checking each other out at these early stages.”
So far, only one calf has gone missing in the past three years.
Last fall, one of the staff on the project noticed a bison calf was no longer with its mother and the rest of the main herd. A month or two later, images from one of many remote cameras confirmed the situation.
It is believed the calf died under natural circumstances, such as being killed by a predator, was injured, or simply died in this harsh mountain environment through exposure to many natural hazards including severe weather, steep terrain and challenging stream crossings.
“We assume it was a natural cause of death,” said Heuer.
“The only other thing that could have happened was it left the park, but that would be highly unlikely to leave its mother.”
For the most part, the herd stays within the heart of the reintroduction zone. At times buson bump up against fencing designed to keep them from heading outside the national park onto neighbouring provincial lands where they are unprotected.
“They seem to be staying put for the most part, but that being said, they have deflected off two of our drift fences,” said Heuer. “I think that’s happened 21 times since we released them, so 21 times in 22 months.”
There are patterns of behaviour that suggest they are settling into their new home, such as keying into certain favourite areas.
“They are kind of on these circuits where they’re revisiting them at certain intervals,” said Heuer.
“It’s much more indicative of them having formed a new home range. It’s less exploratory and more of returning to places they’ve already been.”
Bison herds once numbered as large as 30 million across North America, but they nearly became extinct within a single human lifetime. Although many factors led to their near-disappearance, over-hunting was the main cause that left fewer than 1,000 bison.
In the Banff area, bison didn’t roam in the vast herds that were common on the plains, but even in low numbers, as the historically dominant grazers, they helped shape ecosystems.
Considered a keystone species, they alter landscapes in ways that benefit many other plants and animals. For example, bison fur provides insulation for bird nests, bison grazing creates habitat for elk,and they provide a rich source of nutrients for scavengers, bears, and wolves.
As part of the reintroduction project, some tough decisions have already been made. Parks Canada killed one bull and relocated two others for wandering onto provincial lands.
But overall, Parks Canada is happy with the program so far.
“I’m really pleased with how things are going,” said Heuer, adding at the end of the five-year pilot project in 2022, Parks Canada will complete a review to determine whether longer term bison restoration in the area is possible.
“There’s certainly a lot of things that could have gone wrong that haven’t. We’ll just keep doing everything we can to try to ensure that the success continues.”