Pumas in Argentina’s Monte León National Park have learned how to hunt Magellanic penguins. They’re also starting to relax their solitary lifestyle by gathering at the same beachfront buffet, which is changing how big predators share space.
People hunting penguins on a beach in Patagonia
Monte León National Park is on Argentina’s Atlantic coast, which is a rough area with cliffs, scrub, and pebble beaches. The park opened in 2004, giving pumas a chance to come back after being hunted by sheep ranchers for decades.
While the pumas were gone for a long time, another animal moved in. Along about 2 kilometres (1.2 miles) of coastline, which is usually safe from large land predators, tens of thousands of Magellanic penguins built a rare breeding colony.
Researchers started to find penguin bones in scat left on paths and dunes after pumas came back. At first, scientists thought that only one or two cats liked seabird. That idea didn’t last long.
There was a lot more puma activity near the colony than expected, which showed that penguins were being eaten by a lot of different animals, not just a few.
A new study in Proceedings of the Royal Society B shows that these big cats eat more than just penguins. The easy meals are changing how they move, how they interact with others, and how many people live in the area.
Following the new penguin eaters
From 2019 to 2023, scientists used a mix of camera traps, GPS collars, and surveys of dead animals on the ground to keep an eye on what was going on around the colony.
- 14 pumas were given GPS collars.
- Nine of them often hunted penguins.
- 5 stuck to more traditional prey like smaller mammals and guanacos.
- Over the course of several breeding seasons, dozens of penguin kill sites were mapped.
All of this happened on the narrow strip of beach and the scrubland around it in the national park. The team also used cameras to guess how many pumas were in the area.
The number of pumas in the park was more than twice as high as the highest levels ever seen in Argentina. This is a big increase for a species that usually lives in small groups over large areas.
Adult pumas usually stay away from each other and patrol a large home range to make sure they have enough food. That pattern started to break down around the time the penguins came home to Monte León.
The penguin buffet has a seasonal boom and bust.
Pumas that ate penguins moved in a different way than those that didn’t. Their territories grew and shrank with the seasons, just like penguins do when they move.
When Magellanic penguins were on land to breed, the pumas stayed close to the colony and mostly stayed in and around the nesting area. After the birds left for months at sea, the cats spread out across the land, looking for other prey and covering about twice as much ground.
| Season | Penguin presence | Puma behaviour |
|---|---|---|
| Breeding (onshore) | Thousands of penguins on the beach | Penguin-eating pumas cluster near colony, smaller ranges |
| Non-breeding (offshore) | Penguins at sea | Pumas roam farther, ranges nearly double in size |
Cats that are usually alone but suddenly get along with their neighbours
One of the most interesting things we found was how often different pumas ran into each other.
Researchers counted 254 encounters between cats that hunted penguins, most of which happened within about 1 kilometre (0.6 miles) of the colony. During the study period, only four meetings were recorded among pumas that did not eat penguins.
This stark difference suggests that pumas that eat penguins are very tolerant of each other and share space near a reliable food source instead of strictly defending it.
These animals aren’t getting together with other animals like lions do. There is no proof of coordinated hunting or stable prides. Instead, they seem to be overlapping, going through the same areas in quick succession, and sometimes eating in the same area without scaring each other away.
That behaviour is typical of other carnivores in the wild: when food is plentiful and close together, they may become less territorial. There are so many penguins to eat that it’s cheaper to put up with your neighbour than to fight all the time.
An ecosystem that looks like a person and has some surprises
Pumas and Magellanic penguins have both been to Patagonia before. The new thing is the specific combination: a thick colony of penguins on the mainland and a recovering apex predator coming back after being pushed out by livestock ranching.
The system changed twice because of what people did. First, a lot of persecution drove pumas out of most of the area, which made it easier for potential prey to live there. Then, a protected area let predators come back to a place where prey communities had already changed.
Reintroducing or permitting predators to recolonise does not revert an ecosystem to a presumed “original” state; rather, it generates new interactions that require comprehension by managers.
Ecologists who are keeping an eye on Monte León say that the interactions between pumas and penguins are likely to have effects on other animals. If some pumas get a lot of their food from seabirds during certain months, the pressure on their usual prey, like guanaco (a wild relative of the llama), might go down for a while. That could have an effect on plants, smaller herbivores, and even farm animals that live outside the park.
What does this mean for penguins?
It might not be a big deal if pumas eat a lot of animals in a large, well-established colony with about 40,000 breeding pairs. A lot of seabirds can handle losing some eggs, chicks, or even adults and still keep their numbers up.
If pumas start going to smaller or newer colonies along the coast, the picture changes. For these, losing a few dozen breeding adults every year could slow growth or even cause it to go down.
Managers have a difficult job because both pumas and penguins are native, protected species, and how they interact has changed because of what people have done in the past. There is no clear “bad guy” to get rid of. Any intervention—fencing off parts of the colony, changing the routes people take to get there, or controlling the number of pumas—would have pros and cons for both conservation and tourism.
What ecologists mean by “predator density”
Predator density is the number of meat-eating animals that live in a certain area. That number is very high for pumas at Monte León. The number of top predators that can fit into a landscape depends on how much food is available, how much competition there is, and how often humans hunt them.
In this case, the penguin colony is acting like a seasonal food source, which raises the park’s capacity for pumas. That makes me wonder how stable a population that big will be if things change, like if there are fewer penguins or more people messing with them.
Why a “generalist” predator changes its prey
Pumas are generalist predators, which means they can eat a lot of different animals instead of just one. A generalist can quickly add a new, easy-to-catch option to the menu when it comes along, like when thousands of penguins shuffle between nests and the sea.
Pumas can live in a wide range of environments, from mountains to scrublands to coastlines, thanks to their adaptability. At the same time, it makes their behaviour hard to predict when new food sources appear, which makes it harder to plan for conservation.
What might happen next in Monte León
Future research at the park seeks to elucidate the impact of penguin hunting on the broader food web. If penguins make it less necessary for pumas to chase guanacos at certain times of the year, the number of guanacos could go up, which would change the pressure on shrubs and grasses.
Researchers also want to know if young pumas learn how to hunt penguins from their mothers or if they figure it out on their own. If this behaviour spreads, more pumas might start to gather around the colony, which would make it even harder for people to accept that these cats are really solitary.
Monte León serves as a living example for wildlife managers in other places. When big predators come back to places that have been heavily shaped by people, they may have to deal with strange diets, strange social structures, and changing risks for prey species. Parks and nearby communities can get ready for those changes by planning ahead, before the penguin buffet gets too busy.
