But to Serrouya, the lead author of the 2019 paper, the solutions proposed, including the wolf cull, make logical sense. In some of the caribou populations he examined, wolf culling or maternal penning did lead to population growth. “The main point of the [rebuttal] relies on a statistical argument, whereas ours relies more so on logic,” Serrouya told me in an email, adding that both papers share the mission of understanding how to to save mountain caribou.
Even though the authors of the new paper found no statistical support for penning pregnant caribou as an effective way to stabilize all of British Columbia’s caribou populations, Darimont does not dismiss the strategy entirely. “Maternal penning is a strategic investment by local people for many reasons that could very well pay off,” Darimont told me in an email. The practice is spearheaded by certain First Nations communities who traditionally harvested caribou on their ancestral lands. But the rebuttal argues that the original study’s small sample size and lack of focus on ecotypes—specific populations, such as the deep-snow caribou, that depend on unique environments—mean that a solution that works in one caribou population might not work in all of them.
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Perhaps the most important finding in the reassessment is that the best indicators of the mountain caribou’s overall decline are the species’ different ecotypes. The most prominent example is the steep decline of the deep-snow ecotype, a population that depends on arboreal hair lichens present only in forests more than 80 years old, says Toby Spribille, a lichenologist at the University of Alberta and an author of the rebuttal. The deep-snow caribou are behaviorally unique from any other ecotype, able to stand atop snowpack as deep as 15 feet to feast on lichens. “I’d like to see the deep-snow caribou not go extinct,” Spribille says, adding that wolves are only the fourth-most-prominent predator of the deep-snow caribou.
And while the 463 dead wolves represent needless tragedy, the damage from the 2019 study has and will most significantly affect the caribou, the researchers say in the rebuttal. From 2014 to 2019, 350 square miles of crucial deep-snow-caribou habitat have been lost to logging, according to a study in Conservation Science and Practice. “That’s irreplaceable on the timescale that we have left to save the caribou,” Darimont told me. Though the rebuttal comes a year late, the researchers hope that it will influence future policy regarding caribou management.
Wagner, one of the authors of the rebuttal, studies grassland ecology, not caribou. But when she saw the 2019 study, she felt no other choice but to set the statistical record straight. “I just felt a sense of responsibility as a scientist,” she says. Now that the rebuttal is published, she can get back to her research studying a rare type of meadow in Montana, near mountains where caribou once roamed.