At a Glance

Emperor penguins have abandoned what was once the second-largest colony in the world.Changes to conditions of Antarctic's sea ice led to the deaths of most chicks over the past three years.

An important Antarctic breeding ground for emperor penguins has been abandoned within the past three years because of changes to sea-ice conditions, a new report says.

Researchers with the British Antarctic Survey (BAS) used "very high resolution to reveal the unusual findings" at the Halley Bay colony in the Weddell Sea, formerly the second-largest emperor penguin colony in the world, according to a statement.

Satellite imagery showing the reduction in size of the Halley Bay colony in 2018 compared with 2015. The dark markings show penguin guano, and the very dense patches are the penguins themselves.

(British Antarctic Survey)

According to the report published Thursday in the Antarctic Science Journal, the penguins, which used to number between 14,000 and 25,000 breeding pairs, for three consecutive years because of the changes to sea ice.

"In 2016, after a period of abnormally stormy weather, the sea ice broke up in October, well before any emperor chicks would have fledged," according to the statement. The same pattern occurred in 2017 and 2018, leading to the deaths of nearly all the chicks.

"These (satellite) images have clearly shown the catastrophic breeding failure at this site over the last three years," said lead author Peter Fretwell, a BAS remote sensing specialist. "Our specialized satellite image analysis can detect individuals and penguin huddles, so we can estimate the population based on the known density of the groups to give reliable estimate of colony size.”

The site used to be the breeding grounds for about 8 percent of the world's emperor penguin population.

While the Halley Bay colony has all but disappeared, it seems some of the penguins moved to the nearby Dawson Lambton colony, which has markedly increased in size over the past three years.

(MORE: Greenland Ice Sheet Melting Faster Than Scientists Thought, Study Says)

The researchers consider the relocation a positive because they were unsure whether the penguins would actually seek alternative sites.

Still, there is cause for concern because many breeding pairs did not go to Dawson Lambton, where numbers increased from a few thousand breeding pairs to 11,117 pairs in 2017 and 14,612 pairs in 2018, according to the study.

Co-author Phil Trathan, a BAS penguin specialist, said it's "impossible to say whether the changes in sea-ice conditions at Halley Bay are specifically related to climate change, but such a complete failure to breed successfully is unprecedented at this site."

“Even taking into account levels of ecological uncertainty, published models suggest that emperor penguins numbers are set to fall dramatically, losing 50-70 percent of their numbers before the end of this century as sea-ice conditions change as a result of climate change," Trathan added.

A by Stephanie Jenouvrier, a penguin expert at Woods Hole Oceanographic Institution, projected that climate change would decrease the global population of emperor penguins by at least 19 percent by the turn of the century.