Gray Wolves, Not Hunters, Are Primary Drivers of Puma Decline In Northwest Wyoming, According to New Study From Panthera

On heels of gray wolf removal from Endangered Species Act, 17 year study provides first evidence that wolves impact puma survival, refuting previous assumptions

November 10, 2020

Media Contact: Susie Weller Sheppard,, 347-446-9904

New York, NY - A new Panthera study has unveiled the first evidence that gray wolves have a greater negative impact on puma numbers and distribution than human hunters in northwest Wyoming, providing scientists with a vital roadmap for managing both species. Published today in Proceedings of the Royal Society B, the study was led by Panthera, the global wild cat conservation organization, in collaboration with researchers from the University of Hawaii and Victoria University of Wellington (NZ).

Over the course of seventeen years, starting in 2000, scientists monitored the lives of 147 pumas across 2,300 square kilometers of northwest Wyoming, during which the region’s puma population decreased by 48 percent. The study sought to determine which threat, including human hunting, prey availability and gray wolves, was having the greatest impact on puma survival.

While wolves have previously been shown to affect pumas’ prey selection and habitat use, this study provides the first evidence that wolves inhibit the survival of pumas overall, including reducing the species’ reproduction and serving as the primary predator of puma kittens.

Human hunting was also found to contribute to puma decline in the study area. However, given the low level of puma hunting in northwest Wyoming compared to many regions of the Western United States, it was estimated that hunting in this particular system was equivalent to the effects of 20 wolves on puma abundance.

Panthera Puma Program Director, Dr. Mark Elbroch, stated, “These results were surprising. While puma populations clearly mold themselves around wolves, no one would have predicted that wolves curb their numbers more than human hunting.”

Elbroch continued, “The results should impact how we manage pumas in areas where the two carnivores coexist, including whether or not we allow them to be hunted.”

The last pack of gray wolves in Yellowstone National Park was killed in the 1920s, after which elk populations ballooned, leading to intense habitat degradation. Wolves were then reintroduced to Yellowstone in 1995 and 1996, just before the start of Panthera’s Teton Cougar Project, and under the mandate of the National Park Service to restore ecological health to landscapes under their management.

A key cautionary takeaway for state wildlife agencies utilizing hunting as a management tool for pumas is that their populations can decline rapidly where wolves are recovering or being reintroduced. The authors encourage wildlife managers to assess hunting quotas of subordinate carnivores like pumas before reintroducing other top carnivores, to avoid such drastic population declines as seen in the Greater Yellowstone Ecosystem. The study additionally demonstrates the interconnectedness of ecosystems and the need within the fields of conservation and wildlife management for a broader, multi-species strategy, as opposed to single species management.

The publication of these findings comes on the heels of the removal of the gray wolf from the Endangered Species List after 46 years.

Panthera Conservation Science Executive Director, Dr. Howard Quigley, stated, “In no way should these findings be misconstrued as a scientific endorsement of the hunting of gray wolves. Instead, if we are to protect these apex carnivores whose survival is so critical to that of their ecosystems and surrounding human communities, the science clearly indicates that the way forward is to reduce or eliminate the hunting of pumas, or at least be very conservative where they share their homes with wolves.”

The findings have broad implications for ecological work everywhere, coming at a time when wildlife management practices are evolving to encourage coexistence strategies with large carnivores. Elbroch explained, “These results provide insights into North America’s historic ecological systems, suggesting that pumas may have been less abundant than they are today in many parts of the West because wolves controlled their numbers.”

Panthera’s Puma Program works to protect pumas - also known as cougars or mountain lions - in western Washington, the southern Greater Yellowstone ecosystem, California’s East Bay and the area surrounding Torres del Paine National Park in Chile. The seventeen-year Teton Cougar Project in northwest Wyoming utilized GPS collars, motion-triggered cameras and other novel research methods to track puma movements, record new wild behaviors, identify natal dens and monitor kittens. The project’s extraordinary body of research is among the most comprehensive ever compiled on the species.

Although pumas range across 28 countries in the Americas, they are poorly understood and thought to be declining overall. Last month, Panthera estimated that 300 to 600 pumas were killed, injured or negatively impacted by wildfires in the state of California this year.

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