9 May 2022North America
Human disturbance is pitting wolverines against an unlikely competitor: Coyotes
- New research finds that when coyotes and wolverines come into contact, the rarer wolverines lose out.
- Human impacts, such as roads and fossil fuel infrastructure, are pushing both of these predators into closer contact, harming wolverine populations.
- Researchers suggest improving landscape management to take into account wolverines’ needs.
In March this year, headlines across the United States announced the rare sighting of an elusive creature in Yellowstone National Park: the wolverine. In the accompanying photographs, a lumbering, blackish-brown animal stands in profile on a snowy road. The individual, thought to be one of only around 10 wolverines that call Yellowstone home, continued on into the trees and disappeared. But new research in Biological Conservation shows that already-rare wolverines (Gulo gulo) may be imperiled by the expansion of coyotes — with human activity to blame.
Although coyotes rarely make the national news, both coyotes and wolverines thrive in similar habitats, eat similar food, and depend on similar climates. Unlike the wolverine, however, the coyote (Canis latrans) appears in abundance across North and Central America — so much so that the small canines outnumber the largest member of the weasel family by as much as or more than a thousand to one.
One place where wolverine and coyote populations often intersect is western Canada. With rugged mountain ranges, heavily timbered woodlands, and deep snowpack, British Columbia and Alberta offer a perfect refuge for both animals. Still, wolverines and coyotes rarely vied for the same food or habitat — until now.
“[C]oyote ranges have rapidly expanded due to increased exploitation of landscape disturbance, while the continental range of wolverines has contracted,” the study says. (Mongabay reached out for comment to the study authors, and while they agreed to answer our questions, they had not done so by the time this article was published.)
The study went on to explain that it was competition with other animals, like coyotes, that posed the biggest threat to wolverines. But why do the two species seem to be interacting more often, despite always having shared similar habitats? According to the research led by Gillian Chow-Fraser, the boreal program manager at the Canadian Parks and Wilderness Society, the answer is us. Generally speaking, although coyotes and wolverines inhabit the same area, they don’t often naturally cross paths. However, when humans disturb a wolverine’s habitat by building roads, trails, or pipelines, it drives the two species closer together.
Coyotes, naturally social and adaptable, tend to adjust to human presence with relative ease. For example, a recent survey published by NPR showed that up to 4,000 coyotes may be living within the Chicago area alone. Wolverines, on the other hand, are loners. They mingle with humans, and other species, far less effectively.
Part of the Mustelidae family, which also includes ferrets, badgers and otters, the wolverine looks more like a small bear than its weasel cousins. Males weigh from 9-27 kilograms (20-60 pounds) while females tend to be smaller, between 7 and 18 kg (15 and 40 lbs). In terms of height and length, the animals are about the same size as a Labrador retriever, but they certainly don’t share the friendly disposition of America’s most popular dog. Generally solitary scavengers, wolverines have also gained a reputation for being both cunning and vicious. When carrion is scarce, the animals can hunt game much larger themselves, such as white-tailed deer (Odocoileus virginianus) or even other predators like wolf pups (Canis lupis), Canadian Lynx (Lynx canadensis), and, on occasion, coyotes. They are, however, not nearly as adaptable to human impacts as coyotes.
To analyze the landscape shift’s impact on wolverines, the researchers placed camera traps and heat-in-motion digital cameras in 154 spots and gathered data for a total of 35 weeks across the course of several years. They spotted wolverines at 70 sites, and coyotes at 74. After analyzing the results, the team discovered that human activity meant more competition between species, which led to fewer wolverines and more coyotes.
In fact, wolverines and coyotes were twice as likely to compete with each other for food and resources after humans disturb a natural landscape, according to the paper. And, in this case, the fact that wolverines can be natural predators to coyotes does not mean that these increased interactions benefit the wolverines. The mustelid’s preference for solitude and their specific feeding habits creates a clear advantage for coyotes’ social, generalist hunting and scavenging methods.
“Landscape change indirectly affects competition to the detriment of species that cannot adapt to disturbances,” the study says. “Conservation actions need to target the mechanisms of species declines.”
In the end, the researchers concluded, “wolverine occurrence was more likely, and more variable, when and where coyotes were absent.” Which means, by default, that wolverines are more likely to be present in landscapes undisturbed by humans.
To combat the decline of species like the wolverine, the researchers suggested conservation efforts be focused on landscape management, especially outside of protected areas. If zoning committees take wolverine and coyote populations into consideration before approving the building of roads or oil and gas pipelines, for example, some of the potential wolverine losses could be avoided.
Citations:
Chow-Fraser, G., Heim, N., Paczkowski, J., Volpe, J. P., & Fisher, J. T. (2022). Landscape change shifts competitive dynamics between declining at-risk wolverines and range-expanding coyotes, compelling a new conservation focus. Biological Conservation, 266, 109435. doi:10.1016/j.biocon.2021.109435
Banner image of a wolverine by Hans Veth via Unsplash.
Exposing the Big Game 
