Satellite-tracked penguin guano reveals diet shifts linked to Antarctic ice loss
Researchers used decades of Landsat images to read the colour of Adélie penguin guano from space, showing that declining sea ice pushes the birds from fish to krill.
By examining thousands of NASA Landsat images, scientists quantified the colour of Adélie penguin guano to infer dietary composition across Antarctica. Field samples collected on a research vessel were spectrally calibrated, linking pink-tinged guano to higher krill intake. The analysis shows that plentiful sea ice supports fish-rich diets, whereas recent ice loss forces penguins to switch to krill, which yields a rosier guano colour.
Since the 2010s, sea-ice minima have led to fewer fish, lighter chicks, and declining colony numbers in regions dependent on fish. Colonies that maintain fish consumption appear stable or growing, but continued ice loss and competition from whales, gentoo penguins and krill fisheries threaten the species. The work demonstrates how big-data satellite monitoring can track hidden changes in remote ecosystems.
Why it matters
The study provides a novel, remote-sensing method to monitor Antarctic food-web health as climate change reshapes marine ecosystems.
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