Why entire populations of Antarctic seabirds are unable to breed

By James Gamble via SWNS

Extreme snowstorms driven by climate change have left entire populations of Antarctic seabirds unable to breed, reveals new research.

A rise in unusually strong snowstorms means there is nowhere for the birds to safely lay their eggs and nest - causing numbers to dwindle significantly, say scientists.

The breeding grounds, which stretch across hundreds of miles and once held nests numbering in the tens of thousands, are now barren of nests of south polar skua, Antarctic petrel, and snow petrel.

Scientists from the Norwegian Polar Institute also warned that these storms are only predicted to worsen in severity - causing concerns for the populations of these seabirds in the coming decades.

The study, published in the journal Current Biology, focused on the Antarctic mountain regions of Svarthamaren and nearby Jutulsessen.

The regions are home to two of the world's largest Antarctic petrel colonies and are essential nesting grounds for seabirds like snow petrels and south polar skua.

In the 35 years from 1985 to 2020, the colony in Svarthamaren played host to between 20,000 and 200,000 Antarctic petrel nests, around 2,000 snow petrel nests, and over 100 skua nests each year.

The Antarctic birds' prime breeding time falls at the beginning of the year - the perfect time to lay their eggs and build their nests.

However, in the breeding season between December 2021 and January 2022, there were found to be just three breeding Antarctic petrels, only a handful of breeding snow petrels and not a single south polar skua nest at Svarthamaren.

The researchers similarly found that in nearby Jutulsessen there were no Antarctic petrel nests between the summer of 2021 and the beginning of the new year. In previous years, there were tens of thousands of active nests in the area.

The study's authors explained that because the birds lay their eggs on bare ground, too much snow makes the ground inaccessible and renders the raising of chicks impossible.

The birds also have to use their available energy to keep warm and shelter from the extreme snow and winds.

Sebastien Descamps, the lead author of the study and a researcher at the Norwegian Polar Institute, said that whilst the storms have always made breeding more difficult for the seabirds, these low results were shocking and unexpected.

Mr. Descamps said: "We know that in a seabird colony, when there’s a storm you will lose some chicks and eggs, and breeding success will be lower.

"But here we’re talking about tens if not hundreds of thousands of birds - and none of them reproduced throughout these storms.

"Having zero breeding success is really unexpected.

"It wasn’t only a single isolated colony that was impacted by this extreme weather; we’re talking about colonies spread over hundreds of kilometers.

"So these stormy conditions impacted a really large part of the land, meaning that the breeding success of a large part of the Antarctic petrel population was impacted."

The authors added that though at first the climactic shifts in the Antarctic weren't noticed, recent extreme weather across the region has begun to provide worrying evidence of these changes.

And these extreme weather events are only forecasted to increase in frequency in the coming years.

"Until recently, there were no obvious signs of climate warming in Antarctica except for on the peninsula,” Mr. Descamps said.

"But in the last few years, there have been new studies and new extreme weather events that started to turn the way we see climate change in Antarctica."

"When it comes to storm severity, it’s both the wind and the snow accumulation.

"There aren’t many places where we have the right kinds of snow measurements, and it plays an important role in explaining the breeding success of the birds.

"I think our study shows in a very strong way that these extreme events do have a very strong impact on seabird populations, and climate models predict that the severity of these extreme events will increase."