How penguins reshape puma habits in Patagonia

January 22, 2026
By Mathew Burciaga

The grasslands and coastlines of Argentina’s Monte León National Park are undergoing a gradual transformation, as decades of conservation and rewilding efforts are beginning to reverse the ecological impacts of European colonization on the South American puma.

These solitary, apex predators were frequently hunted and poisoned to minimize conflict as sheep farming spread across Patagonia during the 19th and 20th centuries. But over the past few decades, the puma population has begun to rebound as Argentinian policymakers and nonprofit organizations worked to convert former ranches into national parks. 

Conservation ecologist Mitchell Serota (PhD ’24 Environmental Science, Policy, and Management) said the recovery of puma populations in Monte León was expected to restore traditional predator-prey dynamics with guanacos, a native herbivore similar to a llama. Instead, Serota and collaborators from the National University of Comahue and Fundación Rewilding Argentina found that pumas are now subsisting on a hyperabundance of Magellanic penguins (Spheniscus magellanicus) and, in the process, upending their traditional social structures.

A photo of a Puma in a natural environment batting two penguins with its paw.

The high concentration of Magellanic penguins in Argentina’s Monte León National Park has upended the traditional social structures of pumas, according to a recent study led by UC Berkeley ecologists. Photo by Gonzalo Ignazi

“Penguins in Monte León are driving pumas’ space use, sociality, and abundance in ways that we haven’t really seen before,” said Serota, a former graduate student in the labs of ESPM Professors Justin Brashares and Arthur Middleton and the lead author of a recent Proceedings of the Royal Academy of Sciences study detailing the group’s findings. “These behavioral and population changes may have large-scale implications for the Patagonian ecosystem and how we think about the top-down effects of apex predators in altered landscapes,” Serota added.

An Altered Ecosystem

Magellanic penguins historically lived and nested on the islands off the Argentine coast, but gradually spent more time on the mainland as puma populations declined. They can now be found across Patagonia, including in Monte León, which was established as a national park in 2004. Ecologists estimate that at the peak of the breeding season, Monte León hosts 80,000 adult penguins and their offspring, bringing the total to over 40,000 breeding pairs. “There are also more than enough guanacos in the park to sustain healthy populations of pumas,” Serota said. 

Over time, however, researchers observed increasing signs of puma activity within the penguin colonies. Serota, who conducted fieldwork in the park from 2019 to 2023 and is now an ecologist with Duke Farms, a center of the Doris Duke Foundation, said he initially planned to study the traditional predator-prey relationship between pumas and guanacos. But early evidence from the park suggested the interaction between pumas and penguins was far more pervasive than anticipated.

“We talked about this with the park service and with Rewilding Argentina, who said penguin predation happens,” he explained. “But when we started putting up camera traps, we realized that this might be more pervasive than we thought.”

To better understand the phenomenon, Serota and his collaborators tracked 14 individual pumas using GPS collars to determine how their movement patterns and social interactions differed when penguins were present versus absent in Monte León. These observations were combined with images from a network of nearly three dozen camera traps, which researchers used to estimate the number of pumas present in a specific area. Pumas were also categorized based on whether they preyed on penguins.

A collection of photos taken by camera traps showing pumas preying on penguins.

Camera traps captured pumas spending considerable time in or near the penguin colony, a behavior the researchers say greatly reduced the size of their home ranges and more frequent interactions. Photos by Mitchell Serota

Learning to Share

The abundance of penguins in Monte León has fundamentally reshaped how pumas use space and interact with one another, Serota said, leading to behaviors not typically seen in a species largely considered a solitary hunter. Penguins, he points out, are notably easier to hunt than guanacos. “

Pumas that hunt penguins returned to old hunting sites—particularly at the height of penguin breeding season, which runs from October to April—at higher rates than those that do not. GPS data revealed that these pumas tend to concentrate their movements around the colony and remain near it, a stark contrast to the wide hunting ranges of pumas that did not prey on penguins. When the penguins departed, these pumas shifted dramatically, ranging more widely in search of food.

“To give you a sense of how strong a pull penguins are and how important a resource they are for some pumas, we tracked an individual who traveled dozens of kilometers outside Monte León to visit another penguin colony,” Serota said.

A photo of a group of pumas surrounding two penguins in a natural environment.

Penguin-hunting pumas were nearly five times more likely to encounter other pumas within 1 kilometer of the penguin colony. Photo by Gonzalo Ignazi

Based on their analysis, the researchers estimate that pumas congregate in Monte León at a density slightly higher than 13 individuals per 100 square kilometers—a rate more than double the previously highest documented density worldwide for pumas. While much of the seasonal change in behavior can be attributed to penguins, Serota noted that this high puma density persists year-round, supported by the high guanaco density and the absence of human hunting pressure. This easy access to abundant prey has led to what the researchers describe as relaxed territorial boundaries and increased social tolerance.

Pumas are typically solitary predators that interact only during breeding. However, the penguin-hunting pumas were nearly five times more likely to encounter other pumas within 1 kilometer of the penguin colony. “Think of it like a big salmon run stream where many individual brown bears share a stream, except you replace the bears with pumas and the salmon with penguins,” Serota said. “In the same way, there is such a high concentration of resources that there’s little to no risk in sharing them.”

The study provides a powerful example of the unanticipated outcomes of wildlife restoration in altered ecosystems. Guanacos receive a seasonal reprieve from predation during the period when penguins are present, although the effects on their population have not yet been fully studied. Future studies may also determine how the effects of penguin predation can trickle throughout the food web.

“When pumas kill and consume penguins, they are obtaining nutrients that originated in the ocean,” said Emiliano Donadio, science director for Rewilding Argentina and co-author of the study. “The large number of penguin carcasses decomposing on land releases marine nutrients into the soil, linking two different realms—ocean and land—and likely benefiting a myriad of other species beyond pumas.”

Serota said researchers are now working with park management to develop population models that could help anticipate and manage the relationships between the recovering puma population and the expanding penguin colonies.

Read More