BANFF – Wolverines may be ferocious, fearless and feisty, but they’re proving vulnerable to human activities.
Several studies show wolverines, a species with a low reproductive rate, are sensitive to human disturbance and development and require vast secure areas to travel between mountain ranges to maintain viable populations.
Now, a new study is underway in Banff, Yoho and Kootenay national parks, as well as B.C.s northern Columbia Mountains, looking at whether human activities permanently displace female wolverines from what would normally be considered great habitat.
Researchers will look at trends in protected mountain national park lands versus neighbouring unprotected lands in B.C., where recreation, like commercial heli-skiing, and industrial activity such as logging are expanding more and more into remote areas.
Mirjam Barrueto, a PhD student in ecology at the University of Calgary’s biological sciences department, hopes to get information on wolverine numbers and connectivity between regional populations, including different forms of human land use that may affect where female wolverines live.
“The main goal of this research, if all goes well, is to detect breeding females and where they are across a big area in the Columbia Mountains and Banff, Yoho and Kootenay national parks,” she said.
“It will consider human activities and threats facing wolverines, with a focus on commercial heli-skiing and cat-skiing and forestry. We aim to estimate abundance overall and for females, particularly.”
Wolverines, the largest species of the weasel family, aren’t very big, but they’re known to be big on attitude. The Committee on the Status of Endangered Wildlife in Canada lists them as a species of special concern.
Their numbers are said to be declining in many parts of Canada and, because they are solitary animals and cover such vast amounts of territory, they have been difficult animals to study.
In winter 2017, Barrueto and her team conducted a pilot study, installing 10 sampling stations throughout the large study area, with remote cameras identifying 13 individuals by their chest markings.
Now, they will set up 120 non-invasive baited cameras and hair sampling stations to identify individual wolverines through photos. Fieldwork gets underway this year, ending in 2020. The stations are also equipped with wire to collect wolverine hair for DNA analysis so they can identify individual animals.
One camera takes pictures of the chest and abdomen of wolverines, lured to the area by baited scent to climb a run pole attached to a tree. A second camera shoots overview photos to document wolverines and other animals that visit but don’t climb the tree.
“When we go through the photos, we’ll be able to tell individuals apart and tell if it’s an adult by its size,” said Barrueto.
“If they’re good photos we’ll be able identify breeding females when they are lactating.”
Previous studies show breeding females have specific habitat requirements and are sensitive to disturbances. Young female wolverines, despite being able to travel hundreds of kilometres, usually don’t move too far from where they were born.
Barrueto said wolverines are also very territorial, especially females.
“Their home range is about the size of a grizzly bear, but it’s exclusive,” she said.
Recent population surveys by Andrea Kortello and Doris Hausleitner in the southern Columbia Mountains, south of this new study area, suggested pressure on wolverines populations is continuing to increases across the region.
That study showed most wolverines were within or immediately adjacent to large protected areas – provincial parks, nature and wilderness conservancies – away from human activity and development.
Kortello, who spent about 15 years in the Bow Valley doing wildlife research, including work on cougars and wolverines, said understanding where wolverines are and why is essential for the conservation of the species.
“We wanted to put together a picture of what was happening with wolverine on a really broad scale,” she said at a Bow Valley Naturalists’ meeting in Banff.
“Males have home ranges of 1,500 square kilometres, so if you’re going to study them, you need to be thinking big.”
For that study, researchers used DNA hair from wolverines collected at baited trees to detect wolverines over a 20,000 square kilometre area in the southern Columbia Mountains from 2012 to 2016.
The research detected about 36 individual wolverines in that large area of southeastern B.C., much lower than what they were expecting to find.
“That’s not really many, and some were killed in traps,” Kortello said.
Other research shows wolverine densities in the national parks are higher. Outside national parks, where there is development and human disturbance from logging, oil and gas, infrastructure, roads, recreation, and trapping, it’s a different story.
“We found that the bigger that buffer overlap with protected areas, the more likely you are to find wolverine there,” said Kortello, referring to the Purcell Wilderness Conservancy, Goat Range Provincial Park and Darkwoods Nature Conservancy.
“These protected areas are working. They’re doing what they should because you’re more likely to find wolverine there.”
Kortello’s study looked at potential reasons for where wolverines were, or were not found, including climate, food availability, human disturbance like recreation and industrial activity, as well as trapping mortality.
On the climate question, researchers looked at the importance of a persistent spring snow pack for wolverines.
Human disturbance, such as backcountry recreationists on snowmobiles or helicopter skiing, played a role in where wolverines were found – or not.
“I know if I was a wolverine mom and I had a den way up in some nice cirque and a helicopter came whap-whap-whap over the ridge and dumped a bunch of people and sort of skied all over my den, I might decide to relocate,” she said.
Kortello said a consistent snow pack into May is important, particularly for the food-caching habit of wolverines, known to section off chunks of an animal carcass and hide it deep in the snow for a future meal.
“For an animal that makes a good part of its living as a scavenger, caching those bits in the snow, that increases food availability,” she said.
“With caching, you can stretch out your food and make it last longer – the same way we use our refrigerator to stretch out our food availability between trips to the grocery store.”
Kortello said the most important reason to look at spring snowpack was related to suitable denning habitat.
“In mountainous areas, your typical wolverine den is found near treeline, under boulders or talus or large downed trees, and it’s also under a couple feet of snow,” she said.
“The reason for this is the female has to leave her kits and go on foraging expeditions. And it’s probably for thermal regulatory reasons, probably keeps them warm.”
Researchers also thought food sources, such as mountain goats, caribou and marmot, might be a good predictor of where wolverine would be found. They discovered marmot was indeed important in that area.
“The more marmot habitat, the more likely you are to find wolverine,” said Kortello.
“In the winter, marmots are kind of all cuddled up in the talus slope somewhere. They are probably a reliable food source, probably a steady income.”
Surprisingly, Kortello said caribou proved to be an important food, noting there are fewer than 200 caribou in three separate herds in the region.
“There aren’t that many caribou on the landscape, but wolverine do eat caribou, especially they eat baby caribou, but these animals are totally endangered,” she said.
“The fact we found more wolverine in areas with caribou kind of opens up potential for some synergies. You can protect caribou and that’s good for wolverine.”
The real surprise in Kortello’s work was trapping mortality.
She said two or more wolverines might be trapped, but there’d be more wolverine tracks the following week.
“I think what might be happening there is what ecologists call an attractive sink, which is habitat that’s really good and an animal goes for it and wants to be there but it experiences really high mortality,” she said.
“This is like if you went and bought the nice house on the hill, and it’s in a great neighbourhood and the house was vacant and you moved in, but nobody ever told you what happened to the previous owners.”
