The wolf cull isn’t saving caribou

The wolf cull isn’t saving the caribou, and a new study shows that the plan was based on flawed research.

When the clock is ticking and the future of a species is at stake, governments and conservation managers rely on accurate, verified research to create management plans for those at-risk animals. A recent paper now indicates that a government-sponsored wolf cull in Western Canada was based on statistically flawed 2019 research.

The 2019 study (Serrouya et al.) omitted a routine statistical test and concluded that culling of wolves, a predator of caribou, and the use of maternal pens—fenced-off areas for pregnant females to protect calves—would support the stabilization of rapidly declining populations of caribou. This error led to the destruction of more than 460 wolves over the winter of 2019–2020 in British Columbia, while failing to protect caribou. The new research also points to the importance of considering the genetically and behaviourally unique forms of caribou in future management plans.

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Caribou (Rangifer tarandus) in Western Canada can be broken down into four ecotypes, each a unique subspecies occupying a specific habitat. The Boreal, the Northern Mountain, and the Central Mountain caribou browse on ground-dwelling lichens in areas with little snow, while the Southern Mountain ecotype (a.k.a. the Deep-Snow Mountain caribou) forages for lichens off trees in areas with up to three to four metres of snow cover.

Alarm bells went off for Lee Harding, the lead author on the new research and a retired Canadian Wildlife Service biologist, when he and his co-authors realized there was no “null model” included in the 2019 study. A null model is a routine statistical analysis used to determine how likely it is that a result would be observed by random chance. When the authors ran the original 2019 data through a null model, they found that “there was no statistical difference at all between the so-called treatments of wolf culling and/or maternal pens versus random chance,” says Harding.

Harding and his co-authors also reanalyzed the available data and found that caribou ecotype is a better predictor of population trends than the adaptive management scenarios investigated in the 2019 paper. This indicates that instead of using a one-size-fits-all management strategy, government scientists should have instead carefully considered the individual needs of different caribou ecotypes.

Something else was bothersome about the 2019 study: it didn’t take into account the rise in popularity of winter motorized recreation and the impact that this has had on Deep-Snow Mountain caribou. Harding says that when snowmobilers and heli-skiiers venture into the same prime habitat used by these caribou, they can force the animals into subpar habitat. To support the recovery of caribou populations, British Columbia did enact snowmobile closures across mountain caribou range starting in 2009, but the 2019 study did not factor these restrictions into its research.

With this new research, Harding is hopeful that B.C. and the federal government will reassess the current management plan, “that the blind faith support for wolf culling and maternal pens that were espoused by Serrouya et al. is not necessarily applicable for every place or every ecotype of caribou.”

In a press release from the Raincoast Conservation Foundation, one of Harding’s co-authors, Chris Darimont, a professor in conservation science at the University of Victoria and the foundation’s science director, agrees: “If managers are interested in using the best available evidence to inform policy, these findings should trigger an immediate re-evaluation of expensive, socially contentious—and ultimately ineffective—policy.” He adds: “Unless governments move quickly to protect the remaining and irreplaceable habitat, it will continue to vanish at astonishing rates, setting up increasingly desperate conditions from which caribou will never recover.”

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