Gentoo Penguins Are Actually Four Different Species, Scientists Say, Revealing They’re Not Quite ‘Winners’ of Climate Change After All

A new study indicates the adaptable birds evolved into distinct lineages as isolated populations shifted to match their environmental conditions over time. The work has implications for how conservationists assess threats to gentoos

Carlyn Kranking | Associate Web Editor, Science

May 20, 2026 3:09 p.m.

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With white bellies, dark backs and a distinctive light patch above their eyes, gentoo penguins might all look the same at first glance. But according to new research pulling together physical, behavioral and genetic evidence, the birds should be split into four species.

“The differences are not immediately obvious to the eye,” Juliana A. Vianna, a biologist at Chile’s Andrés Bello National University, tells Smithsonian magazine.

“When you look more closely,” says ecologist Jane Younger, of the University of Tasmania in Australia, “at their genomes, measurements, ecology and environmental niches, it becomes clear that they are following different evolutionary paths.”

In late April, Vianna, Younger and 20 other researchers published a study in the journal Communications Biology that argues gentoo penguins are not a uniform group. The scientists suggest that three subspecies of gentoo that are recognized today should all be full species in their own right. They also propose adding a fourth species that has never been recognized before. Three of the four species are at risk of habitat loss as climate change warms the southern polar region.

Rising temperatures and volatile sea ice are putting many penguins across Antarctica at risk. Several, including chinstrap and Adélie penguins, are largely dependent on krill. These shrimp-like crustaceans rely on sea ice for shelter and food, as they eat algae that grow in and on it. But with climate change leading Antarctic sea ice to decline, these krill—and in turn, the penguins—are having a harder time finding food.

Gentoo penguins, however, appear to be adapting well. As flexible eaters, they have diets that are not entirely centered on krill, making them more resilient to climate changes. They have been expanding south as warming temperatures make more habitats available to them, and gentoo numbers, especially along the Western Antarctic Peninsula, have been growing. All this has led some experts to consider gentoos a rare beneficiary of climate change. The new study, however, suggests the story is not so simple.

“That broad picture masks very different regional realities,” Younger says. “Some gentoo penguins are thriving, while others are declining,” and recognizing the four species brings that to light. To put it simply, she adds, “Gentoo penguins are not one climate-change ‘winner.’ They are distinct species facing different threats and different futures.”

To paint this new picture of gentoos, the researchers sequenced the genomes of 64 penguins from ten breeding colonies spread throughout the gentoo’s full geographic range. Beyond genetic analysis, they looked at the birds’ physical measurements, coloration, feeding behavior, diet, breeding timing and vocalizations.

The result, they found, is four distinct penguin species, separated by geography. The northern gentoo, or Pygoscelis papua, lives on the Falkland and Martillo Islands of South America. These penguins thrive in the warmer and saltier waters north of the polar front, along with the eastern gentoo, or Pygoscelis taeniata, which dwells on the sub-Antarctic Crozet, Marion and Macquarie islands.

Farther south, the newly described species, Pygoscelis kerguelensis, forms the southeastern lineage. Its small population evolved on the sub-Antarctic Kerguelen Islands in the southern Indian Ocean. Finally, the southernmost and most populous species, Pygoscelis ellsworthi, lives in icy conditions below the polar front in coastal Antarctica, the Antarctic Peninsula and South Georgia Island.

The species’ body sizes become progressively smaller the closer they live to the South Pole. They also show distinct adaptations—the southern gentoo, for instance, which lives in the coldest area, has genes tied to temperature regulation, storing fat and perceiving light. The eastern gentoo has genes that might support saving energy during long dives in low-productivity waters, while the northern gentoo’s genetic changes are centered around digestion and may support foraging behavior.

“This study highlights how amazingly adaptable gentoo penguins are, so much so that populations that become isolated can become specialized to thrive in different contexts,” says Heather Lynch, a quantitative ecologist at Stony Brook University who has researched gentoo penguins and was not involved in the new study.

Some of the study’s authors had previously proposed splitting the gentoo penguin into as many as six separate species, but the new paper represents a consensus based on the latest data, according to a statement from the University of California, Berkeley. Younger co-published one of those earlier papers, arguing for four gentoo species in 2020. Her previous work, she says, “showed that gentoo penguins should be split; this new study gives us a much deeper evolutionary and ecological explanation for that split.”

Technically, the newly described species are now valid, Vianna says, but she expects they will spark scientific discussion. “The next step is for these species to be assessed and accepted by major avian taxonomic committees and incorporated into official global bird species lists,” she notes.

Separating the gentoo penguin into four species has implications for how experts count and manage the birds. “Dividing the species would suggest that we should be tracking these separately,” Lynch says, “and that gains in some areas cannot be thought of to offset declines in other areas.”

While the southern gentoo of the Antarctic Peninsula might expand its range in the coming years, the other lineages are poorly monitored or in decline—and those on the sub-Antarctic islands are projected to lose habitat with climate change, according to the paper. Gentoo penguins on the Falkland Islands were hit with avian influenza in 2024, and the population on Macquarie Island is dwindling.

When scientists considered all these groups to be the same species, they overlooked the threats that might affect just one lineage. “Recognizing these distinct species is particularly urgent to ensure that vulnerable populations are properly monitored, assessed and protected,” Vianna says.

Carlyn Kranking | | Read More

Carlyn Kranking is Smithsonian magazine's associate web editor for science.