Between 2011 and 2025, the chinstrap penguin population on Zavodovski Island plummeted by 63 percent, with more than 680,000 breeding individuals vanishing from what was once the world’s largest colony. As detikTravel reported, research published in Current Biology and led by the British Antarctic Survey attributes this sharp decline to climate-driven ocean warming that forces essential krill populations southward, out of reach for breeding chinstraps.
Shifting Populations on Zavodovski Island
Located in the remote South Sandwich Islands in the southern Atlantic Ocean, Zavodovski Island once supported staggering numbers of seabirds. Surveys conducted in January 2011 estimated the island hosted approximately 1.09 million breeding chinstrap penguins alongside roughly 338,000 macaroni penguins, according to figures detailed by Koran Jakarta and ANTARA News. By 2025, however, drone imagery, satellite data, and aerial photography revealed that the chinstrap count had dropped to 402,000 individuals.
This dramatic contraction stripped the volcanic island of its crown as home to the planet’s largest penguin colony. That title has now shifted elsewhere in the Antarctic. Data from 2018 indicates that the Adélie penguin colony at Cape Adare in the Ross Sea holds more than one million individuals, making it the current global leader, as noted by Koran Jakarta and CNN Indonesia.
| Species | 2011 Population Estimate | 2025 Population Estimate | Observed Trend |
|---|---|---|---|
| Chinstrap Penguin (Zavodovski) | ~1.09 million | ~402,000 | Down 63% |
| Macaroni Penguin (Zavodovski) | ~338,000 | ~433,000 | Up ~30% |
| Adélie Penguin (Cape Adare) | >1,000,000 (2018 data) | >1,000,000 | Stable / Largest Global Colony |
The Thermal Squeeze on Chinstrap Diets
The rapid disappearance of chinstrap penguins is closely tied to changes in the marine food web. Chinstraps rely heavily on Antarctic krill and demonstrate a distinct preference for colder waters when foraging. As human-driven climate change warms the Southern Ocean—with winter temperatures around the Antarctic Peninsula climbing up to 5 degrees Celsius above pre-industrial levels, as reported by CNN Indonesia—krill have migrated southward toward the Weddell Sea.
The penguins face a geographic trap. While their primary food source moves deeper south, the presence of sea ice and a severe lack of suitable northern islands prevent chinstraps from relocating their breeding grounds to follow the krill. “With menghangatnya suhu laut, krill yang menjadi makanan penguin chinstrap telah berpindah ke selatan,” notes Norman Ratcliffe, the lead author of the study from the British Antarctic Survey, explaining how sea ice and a lack of nesting islands block the birds from tracking their prey.
Contrasting Fortunes for Macaroni Penguins
While chinstraps face a steep decline, macaroni penguins on Zavodovski Island tell a different story. Surveys show that the macaroni population increased from roughly 338,000 in 2011 to 433,000 in 2025—a rise of about 30 percent, according to CNN Indonesia. Macaronis now outnumber chinstraps on the island, with a combined total of over 835,000 individuals for both species.
Researchers explain this divergence through dietary flexibility. Macaroni penguins possess a more varied diet, allowing them to adapt better to shifting marine conditions than their chinstrap counterparts. Field observations indicate that the two species do not compete directly for food, meaning the macaroni population’s growth is simply a separate ecological response rather than a displacement of chinstraps. Even so, Norman Ratcliffe notes that the rise of macaroni penguins offers little comfort given the massive overall loss of chinstraps.
Ruling Out the Pompeii Hypothesis
When Mount Curry, the volcano on Zavodovski Island, erupted violently in 2016, scientists initially feared a mass extinction event dubbed the “Penguin Pompeii” hypothesis. Researchers worried that ashfall and lava flows had wiped out the birds overnight. However, field data and tracking studies disproved this theory.
The population decline occurred gradually and consistently over the 14-year span rather than happening in a single catastrophic drop. Furthermore, tracking data showed that the volcanic ash cloud blew toward the northeast, missing the primary areas inhabited by the flightless birds. Field surveys confirmed that chinstraps actively avoided “asphyxia plain,” the specific zone where ash and lava accumulated.
Conservation Status and Future Outlook
The speed and scale of the chinstrap collapse have alarmed researchers. The International Union for Conservation of Nature (IUCN) currently classifies the chinstrap penguin as “Least Concern.” However, scientists argue that the rapid depletion of major colonies like the one on Zavodovski Island warrants a reassessment, pushing for the species to be categorized as endangered.
With ongoing warming trends in the Antarctic region, the ecological pressures facing ice-dependent species continue to mount. As monitoring efforts expand across the South Sandwich Islands, researchers remain focused on whether other chinstrap strongholds are experiencing the same systematic decline.
