A new food web takes shape
Because Magellanic penguins (Spheniscus magellanicus) spend much of their lives at sea, they are unusual prey for a large terrestrial carnivore whose diet is mostly made up of land mammals, such as deer, guanacos (relatives of llamas), and hares. But during their breeding season—roughly September through April—the seabirds huddle on land in large numbers. At Monte León, more than 40,000 breeding pairs nest along a coastline of about two kilometers long.
(What Magellanic penguins are teaching us about survival)
For a puma, whose territory can cover hundreds of square kilometers, this creates an odd situation: an extremely abundant food source, concentrated in a very small area, and available only part of the year. The team found that the population density remained similar—around 13 cats per 100 square kilometers—whether penguins were present or absent. So, penguins did not create more pumas, but reorganized how these cats share space.
Penguin-eating pumas, it turns out, behave quite differently from those who prefer other diets in Patagonia. The study found that bird-eating big cats shared the same area much more frequently than non-bird-eating ones and were not attacking each other as often as one would expect. “In other words, penguin-eating pumas were quite tolerant of the presence of one another,” says Donadio, who is also a National Geographic Explorer.
Such tolerance was a surprise, given the pumas’ loner stereotype. In Patagonia, these big cats are out in the open, as they are the top predator. “Unlike Africa, they don’t need to scrum together to take down prey twice or three times their size. And unlike North America, there are no grizzly bears, black bears or wolves, so these cats are not sneaking around in the trees at night like they are up here,” says Jim Williams, who worked for decades as a biologist with Montana Fish, Wildlife and Parks and wrote about the relationship between the seabirds and big cats in his book Path of the Puma.
