The world’s largest penguin colony has shrunk by two-thirds since 2011, possibly because of the climate crisis, a study reveals.
Scientists said the rapid disappearance of chinstrap penguins on Zavodovski, the northernmost of Antarctica’s South Sandwich Islands, increased the risk of wider ecosystem collapse.
“This is a huge population collapse, equivalent to the loss of half a million breeding individuals on this island,” said research leader Professor Norman Ratcliffe, a penguin ecologist at the British Antarctic Survey.
The Guardian revealed in 2020 that chinstrap penguin populations were declining on Low, in the South Shetland Islands, sparking concerns among scientists that “something is broken” in the world’s wildest ecosystem.
The new study, published Wednesday in Current Biology, indicates that the speed of the collapse could accelerate so quickly that this distinctive bird – which gets its name from a black line that extends under the beak from cheek to cheek – may have to be classified as an endangered species.
Zavodovski Island had by far the largest penguin colony in the world, with an estimated 600,000 chinstrap penguins and 90,000 macaroni penguins when the population was measured in 2011. Given the decline between then and 2025, it is likely to have lost this title to Cape Adare in the Ross Sea.
Scientists believe the most likely cause is climate change. Human-caused heating has caused winter temperatures on and around the Antarctic Peninsula to rise 5°C above pre-industrial levels, one of the fastest rises in the world. On June 6, Argentina’s Esperanza base on the Trinity Peninsula recorded a record winter temperature of 15.4°C, about 20°C above normal for this time of year – a margin that scientists described as “absolutely crazy.”
Chinstrap penguins have difficulty adapting because they have a special diet and specific ocean temperature preferences. Tracking data shows that they prefer to feed in the colder waters northwest of the island, where they expect to find Antarctic krill, which makes up the bulk of their diet. But as the waters warm, the krill have moved south into the Weddell Sea.
Macaroni penguins, on the other hand, are less picky eaters and their numbers have increased by 30%, but not enough to compensate for the loss of their chinstraps. Ratcliffe said that was little comfort because if current trends continued, all penguins would run out of space.
after newsletter promotion
He said the loss of chinstrap penguins would have wider impacts on food webs. “Every ecosystem can be thought of as a giant Jenga set, and every component you remove increases the risk of complete ecosystem collapse.”
Scientists have ruled out several other possible causes for the decline. There was no sign that chinstrap penguins and macaroni penguins were competing for food. The closest humans lived thousands of miles away.
Although the island is volcanic and experienced a major eruption in 2016, triggering a “Pompeii Penguin hypothesis” of a sudden population drop, this theory was supported neither by the data, which showed a steady linear decline, nor by observations showing that chinstraps avoided the main “asphyxiation plain” area where ash and lava were deposited.
Gn world
