By the end of the century, 90 percent of emperor penguin colonies could be extinct. British polar researchers say thousands of chicks died during the last brood because the ice melted away from under their feet.
When breeding, emperor penguins depend on stable fast ice – sea ice that is connected to the Antarctic mainland to the south and thus withstands wind and currents. Because newly hatched emperor penguin chicks are anything but seaworthy: their gray down is not waterproof. If the ice melts away from under their feet before they have acquired a thick layer of fat and waterproof feathers, they have little chance of surviving.
But due to climate change, the fast ice and thus the safe breeding grounds for the emperor penguins are melting away. The consequence: a mass death of young animals. British polar researchers observed this last year. They recently published their results in the journal “Communications Earth & EnvironmentIt is the first documented large-scale breeding failure directly related to sea ice melt.
Special breeding behavior
Emperor penguins are the only birds that breed in winter. Because the chicks need the entire spring and summer to fledge – this is due to the record size of the penguins: adult animals are over one meter tall. They put their lives in danger for the long incubation and rearing.
During the breeding season, groups of penguins make a pilgrimage for miles towards the South Pole – away from the open sea and their food source. Once the females have laid their eggs, they exhaustedly make their way back towards the sea, where they can fortify themselves with fresh fish.
The animals breed in large colonies. But many of these communities are under acute threat.
Fathers incubate eggs
It is the penguin males who then incubate the eggs on their feet under their thick abdominal feathers for weeks – an exhausting time of starvation and endurance. The penguin fathers lose a good third of their body weight. In order to lose less energy, the penguin males cuddle up to each other in the hundreds in winter.
As soon as the little emperor penguins hatch after around 60 days, they are fed a milk-like liquid by their fathers. Then the female penguins come back from the open sea and bring their offspring the first fresh fish.
The special feature: The couples recognize each other by their voices and the chick also memorizes the calls of its parents. Now the roles are reversed: the male pushes the chick over the ice so that the mother can continue to warm it under her rump. But this has to be done quickly: just two minutes in the freezing cold can be deadly for the chick.
Babies’ down is not yet water-repellent.
Inventory decreases drastically
This life-threatening undertaking is contested by dozens of emperor penguin colonies every year. New colonies are constantly being discovered – many thanks to satellite images. Earlier this year, the number of known colonies rose to 66.
However, the satellite data also show that many colonies are shrinking dramatically. One of the largest colonies has been observed since the 1980s. Their population has since fallen from 500,000 pairs of penguins to just around 60,000 pairs in 2018.
In four out of five colonies all chicks died
Last year, researchers at the British Institute for Polar Research remotely observed five colonies of emperor penguins breeding in Antarctica’s Bellingshausen Sea. The satellite images showed that this region was hardest hit by the sea ice melt last year. All the ice was gone very early in the summer – long before the chicks fledged. As a result, not a single young animal survived in four of the five colonies. The researchers suspect that the ice had already melted before the chicks were able to develop waterproof plumage.
“Chicks that go into the water are likely to drown,” says study lead author Peter Fretwell. “And if they manage to get back out, they’ll likely freeze to death. If they manage to stay on the ice floes, we assume most of them will drift away and starve because their parents can’t find them.”
90 percent of the colonies could die out
These results support the prediction that 90 percent of colonies could become extinct by the end of the century. In the Antarctic, several penguin colonies have already disappeared completely because the sea ice beneath their breeding grounds suddenly broke up. The most recent observations now show that this fate could threaten more and more colonies in the future.
In the past, emperor penguins have been able to adapt to the loss of sea ice by moving to more stable locations to breed the following year. However, this strategy fails when the sea ice is affected in an entire region – as was the case in the Bellingshausen Sea last year.
Climate change is massively changing the Antarctic habitat
The observations from the last extreme year cannot be directly transferred to the future. But the climate trend shows that the Antarctic ice will probably continue to recede. Also in August 2023, when Antarctica experienced a frigid winter and emperor penguins began breeding again, sea ice extent was again at a record low for that time of year. One can only hope that the chicks will be able to survive again this year, at least in some colonies, so that the emperor penguins can be preserved in the long term.