What was once the world's second largest colony of emperor penguins has not been able to raise chicks for the past three years in what researchers are calling a "catastrophic breeding failure."
Antarctic's Halley Bay colony in the Weddell Sea usually sees an estimated 14,300 to 23,000 breeding pairs each year, which represents up to 8.5% of the global emperor penguin population.
But recent satellite images have shown that the population is crashing, "with almost no breeding success in 2016, 2017 and 2018," researchers wrote in a paper reporting their findings, published Thursday in the peer-reviewed journal Antarctic Science.
"This is the first time we have ever seen an event like this at an emperor colony – both in terms of its scale and its persistence," study co-author Peter Fretwell wrote in an email to USA TODAY. "The occasional breeding failure does occur, but not three years in a row."
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The breeding failures are likely due to changing sea ice conditions, the team said. Normally, the penguins need ice to remain sturdy and stable until December, when their chicks are old enough to fledge, or when they grow feathers.
However, starting in 2016, the sea ice began breaking early, resulting in "complete breeding failure," the team said. In 2018, less than 2% of the recent population was at the breeding site, and most of the birds were at the edge of the sea ice, where emperors do not usually breed or feed their young, the researchers wrote.
"The colony at Halley Bay colony has now all but disappeared," the research team at the British Antarctic Survey said in a statement.
While the changing sea ice can't be linked directly to climate change, study co-author Phil Trathan said the failure was unprecedented at the site.
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"It is interesting that the first year of poor sea-ice conditions immediately followed the strongest El Niño in over 60 years," the team wrote in the paper.
El Niño events are associated with warming in the Pacific that changes weather around the world and can lead to accelerated sea ice melt.
Meanwhile, the nearby Dawson-Lambton Glacier colony, which had been decreasing in size from 2010 to 2015, saw its population shoot up from 1,280 pairs in 2015 to 14,612 in 2018, the study found.
Trathan told the Associated Press that while the team believes many of the birds moved to the other site, it doesn't make up for the loss at Halley Bay. "Not everybody has gone to Dawson-Lambton yet," he told the news agency.
The breeding collapse is also concerning because Halley Bay, located in high latitudes, was previously thought to be an area safe from the harsh effects of climate change, the study notes.
Trathan told the AP it was an area "where in the future you expect to always have emperors."
Fretwell said it's too soon to tell if sea ice changes that affected Halley Bay would affect Dawson-Lambton, too.
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"What we do predict is that, over the next few decades as Antarctic warms, many emperor penguin colonies will have similar challenges," he wrote in an email to USA TODAY.
Emperor penguins are the largest penguin species at an average of 45 inches tall and up to 88 pounds, according to National Geographic. They're listed as a "near threatened" species on the International Union for Conservation of Nature Red List.
Follow USA TODAY's Ryan Miller on Twitter @RyanW_Miller
This article originally appeared on USA TODAY: 'Catastrophic breeding failure': Second largest emperor penguin colony 'all but disappeared'