A catastrophic die-off of emperor penguin chicks has been observed in the Antarctic, with up to 10,000 young birds estimated to have been killed.
The sea-ice on which the chicks were being raised broke up before they had fully developed the waterproof feathers needed to swim in the ocean. The birds most likely drowned or froze to death.
The event, in late 2022, occurred in the west of the continent in an area fronting on to the Bellingshausen Sea.
It was recorded by satellites.
Dr Peter Fretwell, from the British Antarctic Survey (BAS), said the wipeout was a harbinger of things to come.
More than 90% of emperor penguin colonies are predicted to be all but extinct by the end of the century, as the continent’s seasonal sea-ice withers in an ever-warming world.
“Emperors depend on sea-ice for their breeding cycle; it’s the stable platform they use to bring up their young. But if that ice is not as extensive as it should be or breaks up faster, these birds are in trouble,” he told BBC News.
“There is hope: we can cut our carbon emissions that are causing the warming. But if we don’t we will drive these iconic, beautiful birds to the verge of extinction.”
Dr Fretwell and colleagues report the die-off in the journal Nature Communications Earth & Environment.
The scientists tracked five colonies in the Bellingshausen Sea sector – at Rothschild Island, Verdi Inlet, Smyley Island, Bryan Peninsula and Pfrogner Point.
Using the EU’s Sentinel-2 satellites, they were able to observe the penguins’ activity from the excrement, or guano, they left on the white sea-ice.
This brown staining is visible even from space.
Adult birds jump out on to the sea-ice around March as the Southern Hemisphere winter approaches. They court, copulate, lay eggs, brood those eggs, and then feed their nestlings through the following months until it’s time for the young to make their own way in the world.