Study Helps Explain How Wolf Removal Can 'Unravel' Key Ecological Systems

As U.S. conservationists continue to fight for federal protections that would cover gray wolves in the northern Rocky Mountains, research released Wednesday highlights just how important the apex predators are to the western United States.

The study was published in the journal BioScience and led by William Ripple, a scientist at Oregon State University (OSU) and the Conservation Biology Institute known for his work on trophic cascades and carnivores as well as his demands for climate action.

The paper uses gray wolves to show the trouble with "shifting baselines," which, "in ecology encapsulate the gradual and often unnoticed alterations in ecosystems over time, leading to a redefinition of what is considered normal or baseline conditions."

As the study details:

Gray wolves (Canis lupus) in North America have experienced a substantial contraction of their historical range, at one point almost disappearing from the contiguous 48 United States. However, their conservation is important in part because of the potential cascading effects wolves can have on lower trophic levels. Namely, the proliferation and changes to behavior and density of large herbivores following the extirpation or displacement of wolves can have major effects on various aspects of vegetation structure, succession, productivity, species composition, and diversity, which, in turn, can have implications for overall biodiversity and the quality of habitat for other wildlife.

"By the 1930s, wolves were largely absent from the American West, including its national parks," Ripple said in a statement. "Most published ecological research from this region occurred after the extirpation of wolves."

"This situation underscores the potential impact of shifting baselines on our understanding of plant community succession, animal community dynamics, and ecosystem functions," he continued.

The researchers examined journal articles, master's theses, and Ph.D. dissertations from 1955 to 2021 that involved field work in national parks in the northwestern United States for whether they included information on the removal of gray wolves.

They found that "in total, approximately 41% (39 of 96) of the publications mentioned or discussed the historical presence of wolves or large carnivores, but most (approximately 59%) did not. The results for the theses and journal articles were similar."

While the researchers focused on wolves, Robert Beschta, co-author and emeritus professor at OSU, noted that "in addition to the loss or displacement of large predators, there may be other potential anthropogenic legacies within national parks that should be considered, including fire suppression, invasion by exotic plants and animals, and overgrazing by livestock."

Ripple stressed that "studying altered ecosystems without recognizing how or why the system has changed over time since the absence of a large predator could have serious implications for wildlife management, biodiversity conservation, and ecosystem restoration."

"We hope our study will be of use to both conservation organizations and government agencies in identifying ecosystem management goals," he added.

"Nature is a really complex tapestry... When you start to pull threads out like you remove apex predators, the whole thing begins to unravel."

Amaroq Weiss, senior wolf advocate at the Center for Biological Diversity (CBD), welcomed the study, telling Inside Climate News that "I think this is a really important paper, because sometimes science advances at a certain rate without a self-introspection."

"Nature is a really complex tapestry," she said. "It's woven together by threads that hold it together and keep it strong. When you start to pull threads out like you remove apex predators, the whole thing begins to unravel."

The paper comes amid a wolf conservation battle that involves Weiss' group. In February, the U.S. Fish and Wildlife Service (FWS) determined that Endangered Species Act protections for the wolves in the northern Rocky Mountains were "not warranted."

Two coalitions of conservation organizations, including CBD, swiftly filed notices of their intent to sue over the decision if FWS didn't change course. After the legally required 60-day notice period passed, they filed the lawsuits in April.

Earlier this week, "the cases were voluntarily dismissed and immediately refiled to avoid any potential arguments from the defendants that the plaintiffs failed to give the secretary of the interior proper 60-days' notice under the Endangered Species Act," Collette Adkins, an attorney who leads CBD's Carnivore Conservation program, told Common Dreams in an email Thursday.

"Plaintiffs believe that their case was properly noticed," she said, "but we refiled to avoid any further disruption of the proceedings."