Snowstorms prevent reproduction of seabirds in Antarctica – 04/10/2023 – Environment

Extreme weather events, which have become increasingly intense and frequent in recent years, may be preventing seabirds in Antarctica from reproducing.

With more frequent snowstorms and high rainfall during the breeding season, entire populations of birds on the Antarctic continent have been affected to a drastic drop in their reproduction.

Scientists, when evaluating the period from December 2021 to January 2022, recorded the absence of nests with eggs of at least two species of birds, the Antarctic petrel (thalassoica antarctica) and the southern miller (stercorarius maccormicki).

A third species, the snow petrel (Pagodroma nivea), which had 57% of active nests from 2011 to 2020, reached just 4% from 2021 to 2022.

The data were presented in a scientific article published in the specialized journal Current Biology on the 13th by scientists from France, Norway and the United Kingdom.

According to the authors, the complete absence of reproduction during a breeding season in seabirds is an extremely rare event, which raises a warning about the effects of climate change on animals and ecosystems.

To assess bird reproduction, the researchers analyzed two locations in the region known as Queen Maud Land, a territory on the Antarctic continent claimed by Norway since 1938, although it is not internationally recognized as belonging to the Nordic country.

The studied sites are about 90 km from each other, close to the Maitri research station, on the Antarctic coast.

The first site, known as Svarthamaren, had an average snow cover of 25 cm in January 2022, and only three Antarctic petrel nests and none of the southern miller were found (versus more than 20,000 Antarctic petrel nests and from 40 to 70 of southern miller in previous years). The southern miller feeds on petrel chicks, so its absence in the region can be explained by the lack of prey.

As for the third species, snow petrel nests had a reduction of more than 93%, from 57%, in the decade from 2011 to 2020, to only 4% in 2022.

In the locality of Jutulsessen, the second analyzed, no Antarctic petrel or southern miller nests were found, and the record of active snow petrel nests fell by 33%, in the period from 2008 to 2021, to just 3% in 2022.

According to Sebastien Descamps, a researcher at the Norwegian Polar Institute and first author of the study, seabirds are, in general, extremely faithful to their breeding grounds, returning year after year to the same location and even the same rock to lay their eggs.

“When things go wrong, the birds stop reproducing and return to the sea until the next season, but they rarely change their nesting location. It is clear here that the effect of the storm on reproduction was widespread and extremely strong”, he says.

Analyzes of previous decades already showed a deep drop in the reproduction and population of seabirds in the region in recent years, but there was no evidence of a relationship with snowstorms, which is very worrying.

If, in 1980, there were more than 150,000 active Antarctic petrel nests, that number dropped to less than 50,000 in the late 1990s and around 41,000 in 2017 and 2018.

“Population declines can have a variety of causes, such as dwindling marine resources, flooding and extreme heat waves, but there was no data on snowfall. What we saw in the research is that extreme snowstorms are an additional stressor for reproduction. and survival of the animals”, he says.

Several studies conducted in the region show that climate change is already triggering the occurrence of climate events such as melting glaciers, rising temperatures and rising Antarctic sea levels, which affect the animals that live there.

Although the research has observed a correlation between the most intense snowstorms and the absence of nests, Descamps says that the models do indicate more extreme weather events like these as a consequence of climate change, but with the study data alone it is not possible still draw such conclusions.

“It is very likely that this is happening at some stage, but they still remain as predictions, not facts,” he says.

_{The Planeta em Transe project is supported by the Open Society Foundations.}