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Sunday, March 4, 2018
On Friday, scientists announced in Scientific Reports that roughly 750,000 breeding pairs of Adelie penguins (Pygoscelis adeliae) have been discovered on Antarctica’s Danger Islands. These findings have required scientists to adjust their understanding of the birds’ population trends, which had been believed to be in overall decline.
The survey included both manually counting nests on the ground, counting nests by eye in panoramic photos, counting nests using an algorithm, and analysis of patches of penguin guano in images collected using drones and satellites.
The researchers reported the Adelie penguin population has declined 70% in South Orkney Islands, South Shetland Islands, Western Antarctic Peninsula in the last several decades, whereas their population has been increasing to the south of Marguerite Bay. They describe the population increase in the northerly Danger Islands as an unusual find.
In remarks to BBC News, study co-author Tom Hart of Oxford University said, “It’s a classic case of finding something where no one really looked! The Danger Islands are hard to reach, so people didn’t really try that hard”.
“They also appear to have not suffered the population declines found along the western side of Antarctic Peninsula that are associated with recent climate change,” added fellow researcher Mike Polito of the University of Louisiana.
The Adelie penguin, along with the emperor penguin, is one of only two species of penguin to live in Antarctica year-round. Large groups of gentoo and chinstrap penguins were also observed during the survey. The study authors believed the Adelies may act as a sentinel species: that they could be used to estimate changes in other, less easily observed populations. Although the number of Adelie penguins has dropped by about 70% in some parts of Antarctica, these researchers speculated at least some of them may have shifted location rather than perished, or the population may have decreased and then increased again.
These islands have not experienced environmental changes on the same magnitude as other parts of Antarctica and remain surrounded by sea ice even during the southern summer, which may preserve the krill and other animals the penguins like to eat. These penguin colonies were not found earlier because the Danger Islands are very hard to reach.
The Danger Islands are part of a proposed marine protection area. “Whether they’ll be in or out, we don’t know but at least now the people making those decisions will understand how important this area is,” co-author Heather Lynch of Stony Brook Unviersity told the press.
A 2017 report by the University of Adelaide placed the total Adelie penguin population of Antarctica at about 6 million.