A study in Yellowstone National Park reveals that wolves frequently take over kills made by cougars, leading to tense interactions between the two predators. Cougars adapt by shifting their hunting focus to smaller deer to avoid encounters with wolf packs. The research, based on nine years of GPS tracking, highlights how these apex predators coexist amid changing prey availability.
Researchers have uncovered details about the competitive dynamics between wolves and cougars in Yellowstone National Park through an analysis of nine years of GPS data from collared animals and field investigations at nearly 4,000 potential kill sites. The study, published this week in the Proceedings of the National Academy of Sciences, shows that wolves often usurp cougar kills, with about 42% of their interactions occurring at sites where cougars had hunted. In contrast, only one interaction was recorded at a wolf kill site, and cougars never scavenge from wolves.
Wolves made 716 kills, primarily elk (542), bison (201), and deer (90), while scavenging 136 times. Cougars accounted for 513 kills, mostly elk (272) and deer (220), and scavenged just seven times. As elk populations declined, dietary shifts emerged: for wolves, elk dropped from 95% to 63% of their diet between 1998-2005 and 2016-2024, with bison rising from 1% to 10%. For cougars, elk fell from 80% to 52%, while deer increased from 15% to 42%.
To minimize risks, cougars avoid areas with recent wolf kills and prefer terrain with escape options like climbable trees. Between 2016 and 2024, 12 adult cougar deaths were documented, two caused by wolves near their kills, though wolves did not consume the cougars. No wolf deaths were attributed to cougars among 90 recorded.
"In North America and worldwide, carnivore communities are undergoing major changes," said lead author Wesley Binder, a doctoral student at Oregon State University. The findings suggest that coexistence relies on prey diversity and safe terrain rather than overall prey abundance. Wolves were reintroduced to Yellowstone in 1995, while cougars have recovered since the 1960s and 1970s under legal protections, leading to overlapping territories in the western United States.
Co-authors include Joel S. Ruprecht, Rebecca Hutchinson, and Taal Levi from Oregon State University, along with researchers from the University of Minnesota and Yellowstone Center for Resources.
