Massive wolf kill disrupts long-running study of Yellowstone park packs

Hunters are killing gray wolves in the northern Rocky Mountains in numbers not seen since the animals were driven to near extinction in the continental United States in the 20th century. The killing of more than 750 wolves in Montana, Idaho, and Wyoming in recent months—including nearly 20% of the wolves that roam Yellowstone National Park—threatens to undermine a decades-old effort to restore the predators to the landscape and disrupt a long-term Yellowstone research project that has produced influential findings on how wolves help shape ecosystems. Researchers and conservation groups are calling on government officials to rethink the hunts, which have eliminated more than 20% of the wolves living in the three states.

The loss of the Yellowstone wolves “is a huge setback,” says wildlife biologist Doug Smith of the National Park Service, who leads the park’s wolf restoration and study project, which began in 1995. “We had in Yellowstone one of the best models for understanding the behaviors and dynamics of a wolf population unexploited by humans.” Now, he says, researchers will “do what we can to keep the science going—what we have left of it.”

The killings are the result of a change in legal protections for Canis lupus. For decades, the wolves were strictly protected under the federal Endangered Species Act (ESA), but in recent years successful restoration efforts prompted federal officials to ease protections and give state governments a greater say in managing the species. With wolf numbers in the northern Rockies reaching about 3100 in late 2020, several states have legalized or expanded wolf hunts. Legislators in Montana, for example, last year set a goal of shrinking the state’s wolf population to “at least 15 breeding pairs,” the minimum required by the ESA; state rules allow each hunter or trapper to kill up to 10 wolves each season. Idaho also aims to shrink its wolf population and has set no kill limits. Wyoming has nearly achieved its goal of maintaining just 100 wolves and 10 breeding pairs outside of Yellowstone (where hunting is barred).

Biologists say the recent killings won’t cause the regional extinction of wolves, although the U.S. Fish and Wildlife Service (FWS) announced in fall of 2021 that it would begin a 12-month review to determine whether “potential increases in human-caused mortality may pose a threat” to the species. The killings do, however, promise to alter the social structure of wolf packs—and reshape the Yellowstone study, which has produced high-profile findings on how the return of wolves has affected forest ecology and elk, beaver, and songbird populations. As of 31 January, hunters had killed 23 of the roughly 125 wolves that use the park, including four that carried electronic tracking collars placed by scientists. Eighteen were killed in Montana outside the park’s northern borders, where officials had recently lifted quotas, and five were killed in Idaho and Wyoming.

This is not the first time hunters have killed park wolves. In Montana, hunters killed up to seven of the wolves each year between 2009 and 2020. But this year’s large kill “complicates the research as we will now have to account for the confounding effects of hunting,” says Dan MacNulty, an ecologist at Utah State University who studies how wolves interact with elk.

Smith now plans to study how the killing is affecting the Yellowstone packs. Last week, he placed tracking collars on animals in the northern part of the park, hoping to “compare the persistence and reproductive rates” of packs that have lost members to hunters with those that haven’t. Data show pack size can affect wolf health and hunting success, Smith notes. Packs with more than eight individuals “are more resilient” to diseases such as mange, which is caused by mites, and can “have greater prey kill rates and are better at territorial defense.” Smith believes it will take 4 or 5 years for the park’s packs to rebound from the recent losses, and he anticipates park wolves will become warier of humans and likely more difficult for visitors to see.

Scientists, Indigenous tribes, and environmental organizations have raised concerns about the loosened state wolf hunting regulations to FWS. One fear of wolf advocates is that the increased hunting in Montana, Wyoming, and Idaho will prevent wolves from leaving those states and founding new packs in other western states. Still, at least one state, Colorado, is pressing ahead with its own plans to restore the canids to areas west of the Continental Divide.

Because Yellowstone wolves are a favorite attraction, the park’s superintendent, Cam Sholly, has said he is willing “to work with the state of Montana to make the case for reinstating quotas that would protect the [park’s] core wolf population.” But Montana Governor Greg Gianforte (R), who is a trapper, has shown little interest in tightening hunting limits. And the state’s wildlife commission recently declined to close hunting in certain areas near the park, where hunters have so far killed 76 wolves, just below a “threshold” target of 82. “We don’t manage for individual wolves or packs. We manage wolves across landscape and population scales,” says Greg Lemon, a spokesperson for Montana’s wildlife department.

Critics of wolf hunting say state officials have adopted contradictory policies. On one hand, they want to reduce elk populations, which they say have grown too large. Montana, for example, wants to reduce elk numbers from about 170,000 to 92,000. But they’ve also embraced killing a predator that could help them achieve that goal. “Their management objectives,” MacNulty notes, “are at cross purposes.”

Wolf advocates and state officials are also battling over wolf hunt limits in Wisconsin. Early last year, hunters there killed more than 200 wolves—an estimated 20% of the state’s wolf population—in just 3 days, well above the permitted kill of 119 animals. Conservation groups and Indigenous groups then went to court to block a state plan to allow hunters to kill up to 300 wolves in a subsequent hunt. A judge has barred the hunt pending the outcome of the cases. Meanwhile, biologists and volunteers are now conducting an annual Wisconsin wolf survey, which should enable “a better assessment of what the impacts were of the 2021 hunt,” says wildlife biologist Adrian Wydeven of Green Fire, a group that promotes science-based management of natural resources.