King penguins that feed on fish and squid at the northern edges of Antarctica are threatened by global warming, which is cutting down on their food supply, researchers reported on Monday.
King penguins, the second-largest species after emperor penguins, are at the top of the food chain in their sub-Antarctic environment, thriving on small fish and squid rather than the tiny krill and other crustaceans that sea mammals favor.
This makes king penguins good indicators of changes in their ecosystem, scientists said in research published in the Proceedings of the National Academy of Sciences.
Scientists at the CNRS Institut Pluridisciplinaire Hubert Curien in Strasbourg, France, studied king penguins on Possession Island in the southern Indian Ocean over nine years.
The researchers found that high sea surface temperatures in the area where the king penguins spent the winters cut the amount of available marine prey, which in turn cut the survival rate of adult king penguins.
Their study found a 9 percent decline in the adult penguin population for every 0.46 degree F (0.26 degree C) of sea surface warming.
This means these penguins could be at high risk under current global warming scenarios, which predict an average increase of 0.36 degree F (0.2 degree C) per decade for the next 20 years.