King penguins on the Crozet archipelago in the southern Indian Ocean travel south to forage for food around the Antarctic Polar Front, where cold Antarctic waters meet warmer sub-Antarctic seas (pictured, a king penguin diving). Writing in Nature Communications, Bost et al. report that climatic variability can alter the birds' foraging behaviour and population dynamics (C. A. Bost et al. Nature Commun.; 2015).

Credit: Antoine Joris

By tracking king penguins (Aptenodytes patagonicus) for 16 years, Bost et al. found that changes associated with an increased sea surface temperature of just 1 oC pushed the polar front southward, and increased both the distances penguins travelled to forage and the depths to which they dived for food. After large-scale climatic anomalies, their population size also fell. Climate models predict that the front will continue to shift southward, which may threaten penguins and their prey. Footnote 1