Once the largest penguin colony in Antarctica sharply declined. Their number is down by half a million

Zavodovski Island is the northernmost of the South Sandwich Islands. It is located more than 1,900 kilometers from the nearest permanent settlement, so scientists rarely visit it. Two species of penguins live here: Chinstrap penguins, which have a black stripe under their beak, and Macaroni penguins, recognizable by their yellow crests.

In 2011, the island had about 600,000 Chinstrap penguins and 90,000 Macaroni penguins. Thanks to this, the colony was considered the largest in the world. At that time, on some other Antarctic islands, the number of penguins had already decreased by almost half compared to the 1980s figures, but Zavodovski Island seemed to be an exception.

In 2023, researchers from the British Antarctic Survey spent several days studying the birds on the island. They used drones, aerial photographs from an airplane, and special tracking devices attached to the penguins.

Comparing aerial photographs with satellite data, scientists found that from 2011 to 2025, the number of occupied Chinstrap penguin nests decreased by 63%. According to estimates, their number decreases by about 7% annually — this is the highest rate for this species globally, two to three times higher than in other regions.

The head of the study, ecologist Norman Ratcliffe, called it a huge population crash, equivalent to the loss of half a million breeding-age penguins on the island.

Scientists believe that climate change is one of the most likely causes of the population decline. As a result of warming, winter temperatures on and around the Antarctic Peninsula have risen by 5 degrees compared to the pre-industrial period.

Chinstrap penguins find it difficult to adapt to new conditions because their diet is quite specific. They forage primarily in cold waters and feed on krill — small crustaceans that make up the bulk of their diet. However, due to warming, krill has moved further south.

In 2016, a powerful volcanic eruption occurred on the island, which led to the hypothesis of "penguin Pompeii." However, it was not confirmed: the population decline began several years before the eruption, and penguins avoided areas covered with ash and lava.

Meanwhile, the number of Macaroni penguins on the island, on the contrary, increased by 30%. Thus, warming may have affected the two species differently. However, according to Ratcliffe, if current trends continue, over time there may not be enough space for all birds. The disappearance of Chinstrap penguins will also negatively affect food chains.

The scientist compared the ecosystem to a large Jenga tower: if individual elements are removed from it, the risk of complete collapse of the entire system increases.

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