Patagonian pumas are preying on penguins, changing the way big cats interact with each other.
The mountain lion re-established itself in an Argentine national park with a breeding colony of penguins, and the cats quickly began eating the bird. Now it turns out that normally solitary cats that eat penguins tolerate each other more often than expected, according to a new study published in the Proceedings of the Royal Society B on Wednesday (December 17).
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“Restoring wildlife in today’s changed landscapes is more than simply rewinding ecosystems to the past,” said study co-author Mitchell Serota, an ecologist at Duke Farms in New Jersey. “It could create entirely new interactions that reshape animal behavior and populations in unexpected ways.”
Patagonian sheep ranchers drove pumas out of the area in the 20th century. After Monte León National Park was established in 2004, mountain lions began to return. But while mountain lions were gone, other species were adapting to reduced hunting pressure. For example, a group of Magellanic penguins (Spheniscus magellanicus), normally confined to offshore islands, has established a mainland breeding colony of about 40,000 pairs.
Shortly after the park was established, researchers began noticing dead penguins in puma feces. Mountain lions were taking advantage of the altered ecosystem.
“We thought there were only a few people doing this,” said Serota, who conducted the study while a doctoral student at the University of California, Berkeley. “But once we got there…we noticed that a large number of mountain lions had been detected near the penguin colony.”
In the new study, researchers used cameras to estimate the number of mountain lions living near a penguin breeding colony, a 1.2-mile (2-kilometer) stretch of beach in the national park. The researchers also tracked 14 mountain lions with GPS collars and investigated penguin kill sites over several seasons from 2019 to 2023. Nine of the mountain lions tracked hunted penguins, while five did not.
The study found that mountain lions that ate penguins had large variations in their home ranges depending on the season. When the birds were in the national park during the breeding season, penguin-eating cats would stick close to penguin colonies. However, when the birds migrated offshore in summer, their range was about twice as large.
Pumas that ate penguins interacted with each other more frequently than pumas that relied on other prey. The researchers recorded 254 encounters between pumas that both ate penguins, and only four encounters between pumas where neither ate penguins. Most encounters between pumas took place within 1 km (0.6 miles) of penguin colonies.
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Because multiple pumas used this colony as a food source, this difference suggests that pumas that eat penguins tolerate other pumas better than pumas that rely on other prey. This is probably because penguins 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 double the highest density ever recorded in Argentina. Adult mountain lions are usually solitary, establishing 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 will help managers develop management strategies based on how ecosystems actually work today, rather than assuming how ecosystems will work based on the past. “This is essential for conservation planning, as it allows us to design new species,” Juan Ignacio Zanon Martínez, a 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.
Learning how mountain lion behavior affects both cats and penguins could inform future conservation efforts at the park.
For example, mountain lion predation may not have a significant effect on large breeding colonies, but it may affect the growth of new, small colonies. “It’s a complicated situation for the people involved in managing this area, because we have two local people.” [species] “Human activities are changing ecosystems and interacting in a different way than before,” said CONICET biologist Javier Ciancio, who was not involved in the new study.
Serota said that in future research, the team plans to examine how the relationship between pumas and penguins affects other prey animals, such as the guanaco (Lama guanicoe), a relative of the llama.
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