Emperor penguins face bleak times | Polarjournal
Climate change is already having a dramatic impact on some emperor penguin colonies. Last breeding season, in the Bellingshausen Sea, where sea ice broke up before the chicks could develop their waterproof plumage, four colonies suffered total brood failure. (Photo: Michael Wenger)

Down the road, climate change will make it very difficult for emperor penguins to find a suitable location to breed. However, they are more flexible in their choice of location than previously thought, a new study shows.

During their breeding season in the Antarctic winter, they endure the most extreme conditions existing on our planet and are correspondingly demanding of their habitat. The most important component is fast ice as a platform during breeding season – nearshore sea ice connected to the continent or to the ice shelf. Fast ice, however, will no longer be a reliable habitat as warming continues. Bleak prospects for the iconic emperor penguins. Projections suggest that more than 90 percent of emperor penguin colonies could become extinct by the end of the century.

In their interdisciplinary study, an international research team from France, the U.S., Canada, New Zealand and Australia now reveals that at least some of these unique seabirds could survive for a few decades under certain conditions and in certain Antarctic regions.

However, the mere existence of solid ice is not sufficient for this. It must meet certain characteristics: Emperor penguins need a stable, sufficiently large fast ice platform that lasts the entire breeding season and its edge is close enough to open water for foraging. The stability of the fast ice is of particular importance to ensure that the chicks have sufficient time to develop their water-resistant plumage. In addition, other factors must be met to provide a good habitat for emperor penguins, the team noted.

It turns out the main characteristics that define the most desirable emperor penguin habitat are a combination of physical and biological variables — persistence of the landfast ice, its seasonal amplitude, how much it breaks and forms, when it forms, when it melts, the topography of the bottom of the ocean, and how closely they are located to Adélie penguins or other food competitors,” Dr. Sara Labrousse, a researcher at the National Center for Scientific Research (CNRS) in France and lead author of the study, said in a news release by the Australian Antarctic Program Partnership.

Emperor penguins usually return to their breeding colonies, but would presumably be able to search for more suitable habitats should conditions deteriorate. (Photo: Heiner Kubny)

In the current issue of the journal Science Advances, the researchers also describe that emperor penguins are flexible about their choice of habitat. They reached this conclusion after comparing the habitats used by the 55 colonies in Antarctica. These differ significantly in their environmental conditions, allowing the team to identify five geographic habitat types. Within these different regions, however, the differences between the individual colony sites were small.

Of the five habitat types identified, four appear to match the four distinct genetic metapopulations of Emperor penguins – Weddell Sea, Mawson Sea, Ross Sea and East Antarctic – that were previously discerned, the news release states.

To the team of authors, this finding holds hope because it suggests that as sea ice conditions change, emperor penguins may be able to move to other locations if necessary. “However, previous research has already shown that the ability of emperor penguins to disperse and find more suitable climate refuges is limited, and this is supported by the genetic partitioning [within populations, ed.] among Antarctic regions shown in our study,” Dr. Labrousse explained.

However, the current study did not include food availability for emperor penguins, which may also influence their choice of habitat. As sea ice recedes, fishing activities may increase in the future due to new areas opening up, which could increase competition between krill fisheries and penguins.

The researchers based their study for the first time on high-resolution satellite imagery, which they combined with land-ice metrics and geographic and biological factors to examine emperor penguin habitats evenly distributed across Antarctica.

They believe there is a future for these unique birds if sufficient habitat can be preserved with the establishment of protected areas and if sea ice melt can be slowed by drastically reducing greenhouse gas emissions.

Julia Hager, PolarJournal

Link to study: Sara Labrousse et al, Where to live? Landfast sea ice shapes emperor penguin habitat around Antarctica. Sci. Adv. 9, eadg8340 (2023). DOI:10.1126/sciadv.adg8340

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