The retreat of sea ice in Antarctica is changing the diet of Adélie penguins and may be contributing to the reduction of some colonies of the species. The conclusion comes from a study published in the scientific journal Current Biology in July, which analyzed approximately 4,000 satellite images taken over three decades to identify changes in the birds' diet.
The research used images from NASA's Landsat program to analyze guano — penguin feces — accumulated in areas where colonies concentrate. The amount of excrement is so large that it can be identified from space.
More than just the presence of the material, researchers observed its coloration, which provides clues about what the birds are eating. The technique is based on differences between consumed foods. When penguins eat krill, for example, the guano presents a more reddish coloration, while a diet based on fish results in more greenish tones.
