A new article in the journal Ecological Adaptations found wolf culls increased the growth rate of southern mountain caribou herds by about eight per cent per year and were even more effective when paired with additional measures like maternal penning.HO/The Canadian Press
For decades, researchers have been sounding the alarm about southern mountain caribou, a type of woodland caribou that traditionally ranged through parts of B.C. and Alberta and into Washington and Idaho.
As human settlement and industry expanded, the animals’ habitat dwindled, pushing some herds to extinction and leaving others on the brink. In response, governments, conservation groups and First Nations came up with strategies to save them, ranging from killing wolves, which prey on caribou, to setting up pens to protect female caribou and their newborn calves until the calves were more likely to survive in the wild.
Now, a new study concludes wolf culls are one of the most effective ways to protect southern mountain caribou. Published April 17 in the journal Ecological Adaptations, the study found wolf culls increased the growth rate of southern mountain caribou herds by about 8 per cent a year and were even more effective, boosting population growth by up to 16 per cent a year, when paired with additional measures like maternal penning.
Despite those findings, the study is unlikely to quell controversy over wolf culls, which some researchers see as necessary to protect caribou and others decry as a cruel practice that gives governments an excuse to stall on habitat protection.
Clayton Lamb, a wildlife scientist at the University of British Columbia and lead author of the new study, is among those who believe wolf culls are necessary.
“We provide strong evidence that wolf reductions increase the growth rate of caribou,” Dr. Lamb said in an interview before the study was published, adding that caribou numbers have plummeted so far that urgent action is required.
The new study confirms recovery actions are having an impact, resulting in about 1,500 more caribou, an increase of 50 per cent, than if such measures hadn’t been in place, he added.
“These recovery measures have been applied fairly intensely for almost a decade now and because there’s 30-plus herds, it actually adds up to a lot of caribou,” Dr. Lamb said.
“That’s a good news story.”
Southern mountain caribou have been listed as threatened under the federal Species at Risk
Act since 2003. Over roughly 30 years, the population of southern mountain caribou in B.C. and Alberta
declined by 51 per cent, the study found, from about 10,000 in 1991 to fewer than 5,000 in 2023.
Southern mountain caribou status
Population growth without intervention
Legend
Increasing
BRITISH COLUMBIA
Stable
Declining
Final
exterpation
the globe and mail, Source: clayton lamb,
university of british columbia
Southern mountain caribou status
Population growth without intervention
Legend
Increasing
BRITISH COLUMBIA
Stable
Declining
Final
exterpation
the globe and mail, Source: clayton lamb,
university of british columbia
Southern mountain caribou status
Population growth without intervention
Legend
Increasing
BRITISH COLUMBIA
Stable
Declining
Final exterpation
the globe and mail, Source: clayton lamb, university of british columbia
To protect remaining caribou, both the B.C. and Alberta governments kill wolves, through methods that include shooting them from aircraft. The rationale for wolf culls is that activities such as logging and oil and gas development have opened linear pathways through the bush, drawing moose to feed on new growth and wolves that follow, disrupting the predator-prey balance and putting caribou at risk.
In 2019, a paper published in the Proceedings of the National Academy of Sciences compared several recovery actions and concluded that wolf culls, combined with other measures like maternal penning, resulted in the biggest increases in caribous populations.
But those findings were controversial and in 2020, a study in Biodiversity and Conservation pushed back, citing statistical flaws and other problems with the earlier study, including that more than half of the herds in the study area were not discussed.
For the 2024 study, Dr. Lamb and his co-authors – 33 of them, including the lead author of the 2019 PNAS report – aimed to address those critiques, studying 51 years of demographic data from 40 herds to provide a more comprehensive picture than the earlier report.
They concluded that wolf control is likely to be the backbone of interim recovery programs even if habitat protection picks up speed, Dr. Lamb said.
Chris Darimont, a professor in the University of Victoria’s geography department and lead author of the 2020 report that challenged support for wolf culls, worries that studies like Dr. Lamb’s could encourage governments to take a business-as-usual approach.
“If managers believe they have a solution in hand, why do anything different?” said Dr. Darimont, who is also science director of the non-profit Raincoast Conservation Foundation.
Cost is also a factor. The Lamb report estimates wolf reductions would cost “orders of magnitude less” – between $25,000 to $55,000 per additional head of caribou – compared with habitat restoration, at up to $4.4-million per head, or maternal penning, ringing in at up to $336,000 per head. But researchers weren’t able to compare whether habitat restoration would be more or less effective than other recovery actions because, the study said, current efforts to protect and restore habitat have not yet reached the scale researchers say would have an impact on caribou populations.
In 2020, the federal government struck agreements with the province of B.C. and the West Moberly and Saulteau First Nations that included a commitment to protect more than 700,000 hectares of caribou habitat.
That area is a fraction of what has been disturbed and is still being lost, Dr. Darimont said, citing a 2020 report that found critical caribou habitat in B.C. was logged even after it was legally identified under the federal Species at Risk Act.
Jason Fisher, a wildlife scientist at the University of Victoria, also emphasized the need for habitat restoration.
“As the ultimate cause of declines, habitat loss needs to be curtailed and reversed to create a habitat that will self-sustain caribou. Otherwise, we’ll be conducting expensive, highly invasive management actions like this for a long time, perhaps forever,” Dr. Fisher said.
Martin-Hugues St-Laurent, a wildlife biology professor at the Université du Québec à Rimouski, said he supported the conclusions reached by Dr. Lamb and his co-authors.
“Considering that the habitat is unsuitable to caribou, and taking into account the long period of time needed for that habitat to recover, predator management is critically needed,” he said.