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Melting sea ice has a direct impact on Adélie penguin survival

A recent study sheds new light on the vital importance of sea ice for Adélie penguins, particularly during their annual molting phase. 

The research, led by Dr. Annie Schmidt from Point Blue Conservation Science, has revealed a concerning bottleneck in the life cycle of these penguins that is likely to be intensified by the ongoing effects of climate change.

The molting process

The molting process, a critical time when Adélie penguins shed and renew their feathers, has been found to predominantly occur on sea ice. 

This preference makes it a difficult phenomenon to observe, but Schmidt and her team have made headway by tagging 195 adult penguins with geolocating dive recorders over a two-year period. 

The data gathered from these devices, which tracked the birds’ diving behavior between 2017 and 2019, has been instrumental in identifying when and where the penguins molt.

Critical insights

The research has uncovered two primary molting locations in the Ross Sea and noted a worrying trend. 

Satellite imagery and remote sensing data indicate a significant decrease in sea ice concentration in these areas, with the primary molting area showing a consistent decline since the 1980s.

Direct impacts

The study also established a link between the penguins’ return rates to breeding colonies and the availability of sea ice in their molting habitats. 

A 10 percent reduction in sea ice concentration correlated with a 2.4 to 4.8 percent drop in the number of penguins returning. This statistic highlights the direct impact that diminishing sea ice has on the species’ survival rates.

Study implications 

“Our research sheds light on a facet of Adélie penguin’s life that was previously underappreciated,” said Dr. Schmidt. “Understanding the intricate relationships between the environment, particularly sea ice, and all phases of the penguin’s annual cycle is crucial, especially in the context of rapid climate change.”

This study not only highlights the precarious position of Adélie penguins in the face of environmental changes but also underscores the broader ecological concerns that rising temperatures and melting ice pose to Antarctic wildlife. 

Adélie penguins 

Adélie penguins (Pygoscelis adeliae) are best known for their distinctive tuxedo-like plumage. They are one of three species of “brush-tail” penguins along with gentoo and chinstrap penguins.

Here are some more detailed aspects of their biology, behavior, and conservation status:

Physical characteristics

Adélie penguins are medium-sized penguins, standing about 24 inches tall and weighing 8 to 10 lbs.

They have a white belly with a black head and back, and a distinctive white ring around the eye.

Habitat and distribution

These penguins are one of only two penguin species (the other being the emperor penguin) that are native exclusively to Antarctica.

They inhabit the entire coastline of the Antarctic continent, preferring ice-free areas for nesting.


Their diet primarily consists of krill, though they also consume fish and squid. The availability of their prey is closely linked to the seasonal sea ice extent, which affects the entire food web in the region.

Breeding and lifecycle

Adélie penguins are highly social during their breeding season, forming large colonies on ice-free land. They build nests out of stones, and both parents take turns incubating the eggs and feeding the chicks.

After hatching, the chicks fledge about 50 to 60 days, and the adults then head out to sea to feed and undergo their molting process.


Once a year, Adélie penguins go through a complete molt, which takes about three weeks. During this time, they cannot go into the water, and thus they cannot feed. They rely on fat reserves built up prior to this period.


Known for their curious and often bold demeanor, Adélie penguins may approach human visitors without apparent fear.

They are strong swimmers and can dive to depths of over 175 meters, though most of their foraging occurs within the top 50 meters.

Conservation status

Adélie populations are affected by climate change, with warming temperatures and melting sea ice posing significant threats to their habitat.

Other threats include pollution, disturbance from scientific research stations, and fishing activities that can deplete their food sources.

Climate change

The reduction in sea ice due to climate change impacts the availability of krill, which is the primary food source for Adélie penguins.

Changes in sea ice also affect the penguins’ breeding and molting cycles, as noted in Dr. Schmidt’s study.

Conservation efforts

Numerous studies continue to monitor Adélie penguin populations to understand the impact of environmental changes.

Conservation efforts are geared toward establishing marine protected areas, minimizing human disturbance, and managing fisheries to ensure the sustainability of krill populations.

Adélie penguins are a crucial species for Antarctic ecosystems, acting as both predator and prey. They are also considered indicators of environmental change due to their reliance on sea ice and the food webs supported by it. 

Preserving their habitats is not only vital for their survival but also for the overall health of Antarctic marine environments.

The study is published in the journal Proceedings of the National Academy of Sciences.

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