Extreme snowstorms impact breeding success of petrels

Usually, the arrival of the new year is a perfect time for Antarctic seabirds – such as the south polar skua, the Antarctic petrel, or the snow petrel – to build their nests and lay their eggs. However, from December 2021 to January 2022, scientists found nearly no nests in regions such as Svarthamaren or Jutulsessen, which were previously home to two of the world’s largest Antarctic petrel colonies and essential nesting grounds for south polar skua and snow petrels.

According to the experts, this worrisome phenomenon was likely caused by unusually strong snowstorms – triggered by climate change – that interfered with the birds’ ability to breed.

“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,” said study lead author Sebastien Descamps, a marine scientist at the Norwegian Polar Institute. “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.” 

While from 1985 to 2020, Svarthamaren was home to between 20,000 and 200,000 Antarctic petrel nests, around 2,000 snow petrel nests, and more than 100 skua nests annually, in 2021-2022 there were only three breeding Antarctic petrel, a few snow petrels, and no skua nests – a situation resembling that in Jutulsessen, where no Antarctic petrel nests were found in that period despite having shown tens of thousands of active nests in the previous years.

“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 land, meaning that the breeding success of a large part of the Antarctic petrel population was impacted,” Descamps explained.

Since these birds lay their eggs on bare ground, massive snowfall makes egg-laying and chick-raising impossible. Moreover, such storms also have a thermoregulatory cost, forcing birds to spend all their available strength keeping warm, sheltering, and conserving energy.

Although there were no obvious signs of climate change in Antarctica until recently, over the past few years an increasing number of extreme weather events have shown that the southmost regions of our planet are not spared from the devastating effects of global warming either. 

“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,” Descampes concluded.

The study is published in the journal Current Biology.

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By Andrei Ionescu, Earth.com Staff Writer

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