Canada’s imperilled mountain caribou are staging an unlikely comeback, reversing years of decline that pushed populations to the brink. But researchers warn that any sustained recovery comes with a catch: in order to save these ungulates, thousands of wolves will need to be killed in the coming years, highlighting the unenviable task wildlife managers have attempting to manage complex ecosystems.
For decades, mountain caribou – an ecotype of woodland caribou that once ranged from Alaska down to Montana and Idaho – have suffered catastrophic decline. Experts have long cited widespread habitat degradation and increased predation from wolves as the main reasons for these losses.
For researchers, the idea that wolves are the chief villain in the demise of caribou is often misplaced. Logging clearances have done far more to damage the prospects of caribou, removing the animals’ main refuges and food sources. The newly open spaces also lure moose when vegetation sprouts through scars in the landscape. The moose then attract wolves – wily predators that quickly realise they have a far higher (and less perilous) success rate stalking caribou.
But the effects of that predation are stark: populations of southern mountain caribou declined by nearly 50% between 1991 and 2023. Roughly one-third of the region’s subpopulations were extirpated. Governments and First Nations groups have tried in recent years to stem the decline, with wildly varying levels of success.
Eager to learn which actions and policies have worked, researchers have scoured more than half a century’s worth of data on the 40 herds spanning British Columbia and Alberta. They looked at combinations of all possible interventions, including reducing the presence of other mammals such as moose that attract wolves.
Their research, published in the Ecological Applications journal, found that culling wolves was the only recovery action that consistently increased mountain caribou population growth. Critically, the team pointed out that when combined with maternal penning or supplemental feeding, results improved even more.
The results are a rare bit of good news: as of 2023, recovery actions have increased the abundance of southern mountain caribou by 52%, compared with a simulation with no interventions. When predation pressure from wolves was reduced, biologists found “rapid” population growth. As a result, there are now 4,500 caribou in the two provinces and likely 1,500 more than there would have been with no interventions.
The findings, which seemingly run counter to a previous paper that questioned the effectiveness of wolf culls, highlights the challenges of managing caribou populations that exist within a close-knit ecosystem.
Governments have already legislated protected spaces for the caribou and experts agree that restoring the woodland ecosystem to its previous state – towering old growth trees in thick, impenetrable tracks of forest – would have an outsized impact on recovery efforts. But that would take decades – and the caribou are running out of time. In the interim, killing wolves is seen as the best solution.
“If we don’t shoot wolves, given the state of the habitat that industry and government have allowed, we will lose caribou,” Clayton Lamb, one of the report’s co-authors, told the Canadian Press. “It’s not the wolves’ fault.”
The culls remain deeply controversial. In 2020 and 2021, Alberta slaughtered 824 wolves. In British Columbia, 1,944 wolves have been killed since 2015 – at a cost of more than C$10m.
“Shooting wolves to save another species is an incredibly difficult decision,” said Lamb.
