Four emperor penguin colonies have been discovered thanks to satellite images. These colonies, identified for the first time, each number fewer than 1 000 pairs.
By examining satellite images taken between 2018 and 2022 by Sentinel-2 and Maxar WorldView-2, British scientist Peter Fretwell discovered brownish spots on the great white expanses. These spots correspond to the faeces (guano) of animals concentrated in breeding colonies.
The results were published on January 20 in the journal Antarctic Science, bringing the number of known emperor penguin colonies in Antarctica to 66.
The first discovered site is on the north side of the Lazarev platform, on the coast of Queen Maud Land. While a colony had already been reported in 1959 on this piece of sea ice, 64 km from the newly spotted colony, it had disappeared since 2014 and been declared extinct in 2019. According to Fretwell, the colony probably moved as a result of an extension of the ice tongue or a change in sea ice conditions.
A second site is located at Verleger Point, on the coast of Marie Byrd Land in West Antarctica, some 50 km from the former Russian station Russkaya. Although estimated at 500 pairs, it is possible that the number of penguins is different. The population was in fact estimated by hand-counting individual points on satellite images and may well be reassessed.
Located north of the east side of the West Ice Shelf, Verleger Point is the third site identified by Fretwell. According to initial estimates, it comprised 5 000 couples by the end of November 2022. Its remoteness from the coastline probably explains why the site has not been identified by previous surveys.
Finally, the fourth site, Gipps, lies to the south of the Larsen C platform. This tiny colony (200 pairs) was barely visible on satellite images until 2021. The topography had to change following the collapse of a large iceberg for the penguins to move to the open fast ice.
Note that the reformation of the Umbeashi colony, reported as no longer existing in a 2019 survey, reformed in 2021 and 2022.
The four new colonies and the Umbeashi colony increase the total emperor penguin population by around 5 700 pairs. Other discoveries may soon be made, thanks to improved satellite imagery, which will enable the discovery of very small penguin colonies.
Penguin colonies move if their breeding grounds become too unstable due to changes in sea ice and other factors caused by global warming. Sometimes, colonies split up and one group creates a new colony. So it’s not out of question that newly-discovered colonies may in fact have separated from existing ones.
While this discovery is good news in itself, it is unlikely to change the emperor penguin’s status as a near-threatened species, with around 300 000 breeding pairs recorded. And author Peter Fretwell is hardly optimistic. “Predictions of the future emperor penguins population, linked to anthropogenic climate change, are stark. Current models suggest that if CO2 emissions continue to rise at present rates, almost all colonies will be quasi-extinct by the end of the century. The monitoring of populations is crucial to tracking these changes and, if possible, implementing conservation measures.”
This kind of discovery could help scientists better understand where penguins move. This is important information, as colonies are likely to become increasingly mobile in a warming world.
Mirjana Binggeli, PolarJournal
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