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When humans pit the fate of one native species against another, things get violent.

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When humans pit the fate of one native species against another, things get violent.

New research shows that killing wolves helps caribou. Others ask, are wolves paying the price for people’s unwillingness to tackle the real problem—logging.
April 24, 2024

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Sometimes, saving a species is a bloody business. We’ve shot goats to stop them from denuding Galapagos islands and blasted barred owls to keep them from outcompeting endangered spotted owls. New Zealanders have laced entire islands with poison to clear them of invasive rats.  

But the war to save Canadian caribou stands out for pitting the fate of one charismatic native species against another. Over the last 10 years, government-paid sharpshooters in southern British Columbia and Alberta have killed more than 2,000 wolves to reduce predation on the region’s dwindling caribou populations.

The practice is gruesome and controversial, prompting lawsuits and accusations that wolves are paying the price for people’s unwillingness to tackle the real problem—logging of old growth forests. But new research offers a grim lesson in the ways that the human appetite for habitat has made distasteful solutions some of the only ones that work.

At least for the moment, killing wolves might be one of the few effective ways to help caribou. “We really do show that short term interim predator control has bought us time,” says Mark Hebblewhite, a wildlife ecologist at the University of Montana.

Hebblewhite was one of the authors of a 2019 paper that looked at all the ways people have intervened to try to prop up southern mountain caribou, a collection of herds in British Columbia and Alberta and, until recently, a sliver of the United States. This population is listed as threatened under Canada’s Species at Risk Act.

That earlier paper also found that killing animals that prey on caribou—chiefly wolves—was one of the few measures that worked. But the research came under fire. Another group of scientists claimed the supposed benefits of wolf killing might have just been a statistical illusion.

 

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So Hebblewhite and his collaborators amassed a mountain of data to try for a more thorough examination. They collected data about population counts and survival and birth rates for each of the region’s 41 herds. They plugged all the information into a computer model designed to simulate population dynamics that translate into whether caribou numbers rise or fall.

Then they looked for evidence that these changes were influenced by any of the different interventions tried on individual herds: killing predators; supplemental feeding of caribou; killing moose whose rising numbers attract wolves; sterilizing wolves; and protecting pregnant female caribou in pens.

The results were clear. Caribou benefited only when people killed wolves, or paired wolf killing with other measures such as maternal penning. Without shooting wolves, there was no statistical evidence that the other measures provided a clear benefit. All told, the measures added another 1548 animals to a population of around 4700, the scientists reported last week in Ecological Applications.

“Wolf reductions do work well,” says Clayton Lamb, the lead author and an ecologist at the University of British Columbia’s Okanagan campus. “I think there’s strong evidence of that.”

Even critics of the earlier research, and of the wolf killing, acknowledge the strength of the new results. “This is a stronger paper with a much bigger data set, and with no obvious analytical errors,” says Chris Darimont, a conservation scientist at the University of Victoria in British Columbia who is also part of the Raincoast Conservation Foundation, a nonprofit that has opposed the wolf killing.

But Darimont worries that policymakers will use this short-term effectiveness to postpone politically and economically painful decisions to restrict logging. “My concerns is that more harm to ecosystems—and ultimately caribou — will continue when managers believe that these ‘solutions’ are in hand. It seems to be the case that status quo habitat destruction largely continues,” says Darimont.

There is broad agreement among scientists that habitat loss is at the root of the problem. Decades of logging and, in some places, oil and gas exploration, have replaced old growth forests with expanses of open shrubs favored by moose and deer. Wolves move in, aided by roads, to dine on these animals. Caribou are the unfortunate collateral damage as wolf numbers rise.

Hebblewhite echoes Darimont’s concern about continued habitat loss. But he notes that even if logging were significantly curtailed, it can take decades for forests to grow large enough to short circuit this predation cycle. Southern mountain caribou numbers are already far lower than the roughly 10,000 that roamed the mountainous region in the early 1990s. Fifteen out of 41 herds have either vanished or are on the verge of disappearing.

“If we stopped killing wolves, tomorrow, nothing would change, and we revert to catastrophic declines,” said Hebblewhite. “And that’s because the governments of Canada and Washington and Idaho, when caribou used to live here, have done honestly, jack shit to protect caribou habitat in any substantive way. And you can quote me on that.”

Lamb, et. al. “Effectiveness of population-based recovery actions for threatened southern mountain caribou.” Ecological Applications. April 17, 2024.

Photo: Denali NPS

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