Catastrophic reproductive failure in Antarctica endangers emperor penguins

The emperor penguins of the Halley Bay colony in the Weddell Sea, considered until recently as the second largest in the world, have not reared chicks for three years.

Researchers at the British Antarctic Survey (BAS) have been studying very high resolution satellite images to reveal these unusual findings, published in the journal Antarctic Science.

The Halley Bay colony has a number of breeding pairs of between 14,000 and 25,000 each year, or about 5-9% of the world's population of emperor penguins.

The absence of rearing chicks for three consecutive years is badociated with changes in local sea ice conditions. Emperor penguins need stable sea ice to reproduce, and this platform of Ice should last from April when the birds arrive, until December when their chicks are growing up.

Over the last 60 years, sea ice conditions at the Halley Bay site have been stable and reliable. But in 2016, after an unusually stormy period of time, the pack ice broke up in October, long before the emperor chicks fled. This pattern was repeated in 2017 and again in 2018 and resulted in the death of almost every product on the site each season.

The Halley Bay colony has now almost disappeared, while the nearby Dawson Lambton colony has grown considerably, indicating that many adult emperors have already left there, in search of better breeding grounds when environmental conditions have changed. .

The relocation of a large number of birds to a more stable area is encouraging, because until now, it was not known if penguins would look for other sites in response to significant changes in their local environment.

Peter Fretwell, BAS's lead author and remote sensing specialist, said: "In the last ten years, we have been tracking the population of this colony and other colonies in the region using very high-resolution satellite imagery. high resolution.

"These images have clearly demonstrated the catastrophic failure of breeding on this site over the last three years, and our specialized satellite image badysis can detect individuals and groups of penguins. population according to the known density of the groups to be provided, a reliable estimate of the size of the colony ".

Phil Trathan, expert and co-author of BAS BAS, said: "It is impossible to tell if the changes in sea ice conditions in Halley Bay are specifically related to climate change, but such a total failure to recur is unprecedented. .

"Even taking into account levels of ecological uncertainty, published models suggest that the number of emperor penguins will be greatly reduced, losing 50 to 70% of their number by the end of the century due to sea ice conditions. climate change, "he said.