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A cougar hunts among a breeding colony of Magellanic penguins in Argentina’s Monte Leon National Park. | Credit: Serota et al. / Proc B
Patagonian cougars are preying on penguins – and changing the way the big cats interact with each other.
The pumas in question were rehabilitated in an Argentine national park that was home to a penguin breeding colony – and the cats immediately started eating the birds. Now, it turns out that normally solitary cats that eat penguins tolerate each other more often than expected, new research published Wednesday (December 17) in Proceedings of the Royal Society B reports.
The findings suggest that reintroductions like these can have surprising effects.
“Restoring wildlife in today’s changed landscapes does not simply re-enact ecosystems in the past,” said the study’s co-author. The Mitchell Proverbecologist at Duke Farms in New Jersey. “It can create entirely new interactions that reshape animal behavior and populations in unexpected ways.”
Sheep ranchers in Patagonia forced pumas out of the region in the 20th century. After Monte Leon National Park was established in 2004, pumas began to return. But in the absence of cougars, other species have adapted to reduced hunting pressure. For example, a group of Magellanic penguins (Spheniscus magellanicus), usually restricted to offshore islands, has established a mainland breeding colony of about 40,000 breeding pairs.
Shortly after the park was established, researchers began noticing penguin remains in puma scat. Cougars were taking advantage of the changed ecosystem.
“We thought only a few individuals were 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 lot of cougar sightings near the penguin colony.”
In the new study, researchers used cameras to estimate how many cougars lived near the penguin breeding colony, a 2-kilometer (1.2-mile) stretch of beach inside the national park. They also tracked 14 individual cougars with GPS collars and investigated penguin kill sites over multiple field seasons between 2019 and 2023. Nine of the cougars they tracked hunted penguins, while five did not.
Pumas hunt penguins in Monte León National Park, Argentina. The yellow highlight shows the penguin colony. On the right are some photos of cougars entering the colony. | Credit: Serota et al. / Proc B
Cougars that ate penguins had greater variation in their range from season to season, the study found. The penguin-eating cats stayed close to the penguin colony when the birds were in the national park during the breeding season. But they ranged about twice as far when the birds migrated offshore during the summer.
Cougars eating penguins interacted with each other more often than cougars that relied on other prey. The researchers documented 254 encounters between any two cougars that both ate penguins, and only four encounters between cougars where neither cougars ate penguins. Most cougars encounters occurred within 0.6 miles (1 km) of the penguin colony.
Because more cougars used the colony as a food source, this difference suggests that cougars that eat penguins tolerate other cougars better than cougars that rely on other prey, probably because they do not have to compete as much for abundant food. In fact, the researchers found that the density of cougars in the park was more than twice the highest concentration previously recorded in Argentina. Adult cougars are usually solitary and establish large territories to ensure they have enough prey to feed themselves and their kittens.
Understanding how large carnivores behave when they return to ecosystems affected by humans “is critical to conservation planning because it allows managers to … develop management strategies that are based on how ecosystems actually function today, not how we assume they should function based on the past.” Juan Ignacio Zanon Martineza population ecologist at Argentina’s National Council for Scientific and Technical Research (CONICET), who was not involved in the study, wrote in an email to Live Science.
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Knowing how cougars’ behavior affects both cats and penguins could help future conservation efforts in the park.
For example, cougar predation may not have a large effect on large breeding colonies, but may affect the growth of new, smaller colonies. It is a “complex situation for those who do the management of the area, because you have two natives [species] interacting,” in a different way than before human activities changed the ecosystem, he said Javier Cianciobiologist at CONICET who was not involved in the new study.
In future work, Serota says the team will investigate how the relationship between pumas and penguins affects other puma prey, such as guanacos (guanicoe blade), a relative of the llama.