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

Sometimes, saving a species is a bloody affair. We shot mountain goats to prevent them from overrunning the Galapagos Islands, and we shot barred owls to prevent them from outcompeting the endangered spotted owl. New Zealanders painted the entire island with poison to rid them of the invading rats.

But the battle to save Canada’s caribou pits the fate of one charismatic native species against that of another. Over the past decade, government-sponsored sharpshooters have killed more than 2,000 wolves in southern British Columbia and Alberta to reduce depredation in areas where these caribou populations are in decline.

The practice is horrific and controversial, prompting lawsuits and accusations that wolves are paying the price for people’s unwillingness to address the real problem of old-growth deforestation. But new research offers a hard lesson: Humanity’s desire for habitat makes some unsavory solutions the only ones that work.

For now at least, killing wolves may be one of the few effective ways to help caribou. “We do show that short-term, temporary predator control buys us time,” said Mark Hebblewhite, a wildlife ecologist at the University of Montana.

Hebblewhite is one of the authors of a 2019 paper that looked at all the interventions people have taken to protect caribou in the southern mountains. It’s still a small part of the United States. This group is listed as a threatened species under Canada’s Endangered Species Act.

Earlier papers also found that killing animals that prey on reindeer wolves is one of the few effective measures. But the study was met with criticism. Another group of scientists claims the alleged benefits of killing wolves may just be a statistical illusion.

So Hebblewhite and his collaborators collected a large amount of data in an attempt to examine it more thoroughly. They collected population, survival and birth rate data for 41 herds in the area. They fed all the information into a computer model designed to simulate population dynamics, which translates into rising or falling caribou numbers.

They then looked for evidence that these changes were affected by any of the different interventions tried on individual herds: killing predators; supplemental feeding of caribou; killing moose, as their increasing numbers attracted wolves; targeting wolves Perform neutering; and protect pregnant female reindeer in enclosures.

The results are clear. Caribou benefit only when people kill wolves, or combine killing wolves with other measures such as maternal enclosures. If wolves are not shot, there is no statistical evidence that other measures will have clear benefits. All told, the measures added 1,548 animals to a population of about 4,700, scientists reported in the journal last week. Ecological application.

“Reducing wolf populations does have a good effect,” said Clayton Lamb, an ecologist at the University of British Columbia in the Okanagan and the study’s lead author. “I think there’s strong evidence. Prove it.

Even critics of earlier studies and wolf killing acknowledge the power of the new results. Chris Darimont, a conservation scientist at the University of Victoria in British Columbia, says this is a more convincing paper, with a larger data set and no obvious analytical errors.

But Darimont worries that policymakers will use this short-term effect to delay politically and economically painful decisions to limit logging. My concern is that while managers believe these solutions are in hand, more harm to the ecosystem and ultimately the caribou will continue. Darimont said the destruction of existing habitat appears to be continuing.

Scientists generally agree that habitat loss is the root of the problem. Decades of logging, and in some places oil and gas exploration, have replaced old-growth forests with large expanses of open scrub favored by moose and deer. Wolves move in with the help of roads and feed on these animals. As wolf populations increase, caribou become unfortunate collateral damage.

Hebblewhite echoed Darimon’s concerns about continued habitat loss. But he noted that even if clearcuts were significantly reduced, it could take decades for forests to grow long enough to shorten this predation cycle. The number of caribou in the southern mountains has fallen far below the roughly 10,000 that roamed the mountains in the early 1990s. Fifteen of the 41 herds have disappeared or are on the verge of extinction.

If we stopped killing wolves tomorrow, Herbwhite said, nothing would change and our economy would plunge into a catastrophic recession. That’s because the governments of Canada, Washington, and Idaho were all honest about protecting caribou habitat in any substantial way when caribou once lived here. You can quote me on that.

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

Photo: Denali National Park