The once cacophonous squabbles and calls between thousands of Emperor penguins and their chicks at the edge of the Brunt Ice Shelf on the northwest coast of Antarctic has gone silent.
Researchers from the British Antarctic Survey (BAS) have announced that for the third year in a row, breeding pairs of emperor penguins have failed to raise any chicks at the Halley Bay colony. In a paper published in the journal Antarctic Science, the scientists say the colony — at one point the world's second-largest — likely collapsed due to a dramatic loss of stable sea-ice on which to breed.
"We have been tracking the population of this and other colonies in the region for the last decade using very high resolution satellite imagery," lead author and BAS remote sensing specialist Dr. Peter Fretwell said in a statement. "These images have clearly shown the catastrophic breeding failure at this site over the last three years. 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 news isn't all terrible, but it's a warning
The researchers predict emperor penguin populations may decrease by as much as 70% by 2100 due to sea-ice loss. (Photo: Christopher Michel/Flickr)
Based on the satellite imagery, the researchers say the colony of nearly 14,000-25,000 breeding pairs has all but disappeared. But it's not all bad news. The nearby Dawson Lambton colony, scientists note, has dramatically increased in size over the last several years, leading to speculation that a portion of the emperor penguins at Halley Bay has successfully relocated.
While the researchers are encouraged that the penguins are seeking new breeding grounds in response to changing environmental conditions, they're deeply concerned about the loss of Halley Bay. The colony had long been considered something of a "climate change refuge" thanks to its location in one of the coldest areas on the icy continent.
"It is 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," BAS penguin expert and co-author Dr. Phil Trathan said.
Even taking into account levels of ecological uncertainty, Trathan said published models estimate that emperor penguins may decline in population by as much as 50-70% by 2100 due to changes in sea-ice conditions from climate change.
"In a warming world, it will be crucial to better understand the interplay between wind and ice shelf orography, and to appreciate how these factors impact the location of emperor penguin colonies," the researchers conclude in their study. "Understanding how emperor penguins react to catastrophic sea-ice loss will be of crucial importance if one is to predict the fate of the species over coming decades."