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. Trucchi, an evolutionary biologist at the University of Ferrara in Italy.