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A puma hunts among a breeding colony of Magellanic penguins in Argentina’s Monteleone National Park. |Image credit: Serota et al. /processB
Mountain lions in Patagonia are preying on penguins, which is changing the way the big cats interact with each other.
The cougars resettled in an Argentinian national park that houses a penguin breeding colony – and the cats soon began eating the birds. A new study published Wednesday (December 17) in the journal Nature shows that cats that normally live alone are more tolerant of each other than expected when it comes to eating penguins. Proceedings of the Royal Society B Report.
The findings suggest that reintroductions like this could have surprising knock-on effects.
“Restoring wildlife in today’s changing landscapes is not simply about rolling ecosystems back into the past,” said the study co-authors. Mitchell Serotais an ecologist at Duke Farms in New Jersey. “It can create entirely new interactions that reshape animal behavior and populations in unexpected ways.”
In the 20th century, Patagonian sheep ranchers forced pumas from the area. After Monteleone National Park was established in 2004, mountain lions began to return. But in the absence of cougars, other species have adapted to the reduced hunting pressure. For example, a group of Magellanic penguins (wedge lizard), usually restricted to offshore islands, has established a mainland breeding colony of approximately 40,000 breeding pairs.
Soon after the park was established, researchers began noticing penguin remains in cougar droppings. Mountain lions are taking advantage of altered ecosystems.
“We thought it was just a few people doing this,” said Serota, who conducted the research while a doctoral student at the University of California, Berkeley. “But when we got there … we noticed a large number of mountain lions near the penguin colony.”
In the new study, researchers used cameras to estimate how many cougars were near a penguin breeding colony, a 1.2-mile (2-kilometer) stretch of beach in the national park. They also tracked 14 cougars wearing GPS collars and surveyed penguin kill sites over several field seasons between 2019 and 2023. Nine of the cougars they tracked hunted penguins, while five did not.
Cougars hunt penguins in Argentina’s Monteleone National Park. Highlighted in yellow is the penguin colony. On the right are several photos of cougars entering their habitat. |Image credit: Serota et al. /processB
The study found that there are large differences in the activity ranges of mountain lions that feed on penguins in different seasons. When penguins enter national parks during breeding season, penguin-feeding cats stick to penguin colonies. But when the birds migrate offshore in the summer, their range roughly doubles.
Cougars that feed on penguins also interact more frequently with each other than those that rely on other prey. The researchers recorded 254 encounters between any two cougars that both ate penguins, and only 4 encounters between cougars that did not eat penguins. Most encounters between cougars occur within 1 km (0.6 mi) of penguin colonies.
Since multiple cougars use this group as a food source, this difference suggests that cougars that feed on penguins are more tolerant of other cougars than those that rely on other prey, possibly because they don’t have to compete as much for abundant food. In fact, researchers found that the density of pumas in the park was more than twice the highest density previously recorded in Argentina. Typically, adult mountain lions are solitary and establish large ranges to ensure they have enough prey to feed themselves and their kittens.
Understanding how large carnivores behave when they return to human-impacted ecosystems “is critical for conservation planning because it allows managers… to design management strategies based on how ecosystems actually function today, rather than how we assume they should function based on the past,” Juan Ignacio Zanon MartinezA population ecologist at Argentina’s National Council for Scientific and Technological Research (CONICET), who was not involved in the study, wrote in an email to Live Science.
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Understanding how cougar behavior affects cats and penguins could aid future conservation efforts in the park.
For example, mountain lion predation may not have much impact on large breeding colonies, but may affect the growth of new, smaller colonies. It’s a complicated situation for managers in the area because you have two locals [species] interact” in a different way than before human activities changed the ecosystem, said Javier Cianciois a biologist at CONICET who was not involved in the new study.
Serota said that in future work, the team will study how the relationship between cougars and penguins affects the cougars’ other prey, such as guanacos.lama bird), a relative of the llama.
