Emperor penguins on Antarctica forced into refugia during last glacial maximum

Research of biologists published in Global Change Biology indicates that emperor penguins on Antarctica were forced into refugia by extreme cold during the last glacial maximum (~ 19.5 – 16 thousand years ago). By comparing the DNA of fossil emperor penguins with the DNA of living individuals and colonies, the scientists were able to reconstruct the population dynamics of emperor penguins on Antarctica through time. Their results show three mitochondrial clades within emperor penguins at the time of the last glacial maximum, which suggests that these birds were isolated in three small, separate populations and may have survived in refugia such as the Ross Sea. The population sizes of emperor penguins are related to the balance between sea ice available for breeding and open water available for foraging. Sea ice extent around Antarctica was much greater during the last glacial maximum than at present and therefore, reduced food availability resulted in severe losses among populations of emperor penguins.

Journal reference: Younger, J. L., Clucas, G. V., Kooyman, G., Wienecke, B., Rogers, A. D., Trathan, P. N., … & Miller, K. J. (2015). Too much of a good thing: sea ice extent may have forced emperor penguins into refugia during the last glacial maximum. Global change biology21(6), 2215-2226.

Image: Emperor penguin colony foraging along the Weddell Sea, Antarctica. Source: Christopher Michel, Wikimedia Commons.

Emperor Penguin

Emperor penguins (Aptenodytes forsteri) are the largest of all penguins and are adapted to the extreme cold of the ice sheets of Antarctica and the surrounding seas. They are characterized by a black head and backside, with a hint of yellow on their breast and behind their ears. Because of their streamlined bodies and strong flippers, emperor penguins are excellent swimmers, and at sea they can dive to a depth of more than 500 meters, deeper than any other bird. As carnivores, emperor penguins prey on fish, squid and krill, while they are hunted by leopard seals and killer whales as well as large seabirds, which scavenge mainly on chicks. They are very social animals that huddle together in large colonies in order to survive the harsh conditions of their icy environment. Emperor penguins breed in winter and while females go hunting in the Antarctic waters for themselves and their unborn chicks, males keep the eggs warm in brood pouches on top of their feet. Male and female emperor penguins stay together during the full breeding season, but some are even rumored to remain faithful to their partners for life. After an egg hatches, the parents of the newly born chick take turns foraging at sea and raising their chick in the colony.

Information source: National Geographic, WWF

Image: Emperor penguin family on ice along the Weddell Sea, Antarctica. Source: Christopher Michel, Wikimedia Commons.