Their little chicks fast for more than a week while they forage for fish and krill in the waters of the Antarctic polar front, an upwelling where cold, deep seas mix with more temperate seas.
And while king penguins, the second largest penguin species, can swim a 400-mile round trip during that time, they are traveling farther and farther from their nests on the islands near Antarctica, endangering their hungry offspring.
As with so many other species, warmer temperatures are threatening this population, and a new study published today in Nature Climate Change warns that 70 percent of the 1.6 million estimated breeding pairs of king penguins could be affected in this century.
“They will need to either move somewhere else or they will just disappear,” said Emiliano Trucchi, one of the paper’s senior authors. “The largest colonies are on islands that will be too far from the source of food,” predicted Dr. Trucci, an evolutionary biologist at the University of Ferrara in Italy.
The research team developed a model to predict which islands would become vulnerable with warming, and which ones might become better habitats. They then validated their model through historical and genetic data, reconstructing king penguin relocations during previous periods of climate change.
About half of the king penguin population nests on the Crozet and Prince Edward Islands, in the Indian Ocean south of Madagascar, and are projected to lose their habitat by 2100, according to the model. The 21 percent that nest on the Kerguelen Islands in the Indian Ocean and the Falkland and Tierra del Fuego islands close to South America would find their nesting grounds altered and would have to travel farther to find food and so might relocate. But, the researchers said, some of that would be offset by the colonization of Bouvet Island and a few other islands.
Several others are likely to become more habitable, according to the research. But unlike their bigger cousins the emperor penguins, king penguins can’t nest on ice so their choices are limited and may be hundreds or even thousands of miles from their current nesting areas.
It’s a tall order, said Dr. Trucci, who collaborated on the study with the National Center of Scientific Research in France and the Scientific Center of Monaco, as well as Robin Cristofari of the University of Turku, Finland, among others.
Genetically, all the king penguins belong to one population, though they are dispersed by thousands of miles, suggesting they already migrate somewhat among the islands, he said.
Although a 70 percent loss sounds like a lot, it’s probably a conservative estimate, said Jane Younger, an evolutionary ecologist at Loyola University Chicago, who was not involved in the research.
The fish and krill that penguins feed on are subject to overfishing and acidification with climate change, which will probably mean less food will be available in the years and decades to come, she said.
Protecting the fish in the polar front will be crucial for the king penguins, “to ensure they have the best chance of surviving climate change,” said Gemma Clucas, a postdoctoral research assistant at the University of New Hampshire, who was not involved in the new study.
The new model is particularly useful for making conservation decisions, Dr. Younger said. “If there are some islands that are likely to be relatively safe, like those in the south, then we know about that now, and we can potentially protect those from other threats like fishing and tourism — to give animals the best chance of survival,” she said.
Ceridwen Fraser, a marine molecular ecologist at the Australian National University, in Canberra, said that many species are trying to move toward the poles to find cooler homes. “In the northern hemisphere, there’s land and coast at most latitudes, so it’s not too hard for lots of plants and animals to shift north and find places they can live,” said Dr. Fraser, who was not involved in the new research.
But in the south, she said, “you’ve got Antarctica and then you’ve got this whopping great ocean around it, with just a handful of scattered islands.”
She hopes that attention to the plight of the king penguin will encourage people to do more to combat global warming.
“These are kind of poster children for what’s going to happen with climate change,” Dr. Fraser said. “People wouldn’t care as much if it were a slug or a slime mold, but the same sorts of impacts will happen to many different species. In a way it’s good for us to see these impacts happening to animals we love, because it might spur a little bit of action.”