# Zavodovski Island penguin population decline

> Developing situation record from CLSTR: https://clstr.news/situations/zavodovski-island-penguin-population-decline
> Updated: 2026-10-09T17:55:46.000Z. Sources: 21. Developments: 2.

The chinstrap penguin population on Zavodovski Island in the South Sandwich Islands has undergone a massive decline, losing its status as the world’s largest colony. Research from the British Antarctic Survey indicates that the number of occupied nests fell by 63% between 2011 and 2025, a loss of over half a million birds.

Scientists describe the situation as “an enormous population crash,” noting that the island is experiencing the fastest-declining chinstrap population globally, with annual losses of approximately 7%. As a result, the title of the world’s largest colony has passed to the Adélie penguin colony at Cape Adare in the Ross Sea.

Climate change and ocean warming are identified as the primary drivers. A study published in Current Biology, led by ecologist Norman Ratcliffe, attributes the reduction to warming ocean temperatures causing Antarctic krill—the penguins' primary food source—to migrate toward more southern, colder waters. While the penguins prefer foraging in cooler waters to the northwest of the island, the shifting krill distribution has disrupted their food supply.

While a 2016 volcanic eruption on the island was investigated, researchers determined the decline began in 2011, prior to the event. Additionally, a biological feedback loop has been identified where penguin guano fertilizes algae that darkens snow surfaces, potentially accelerating Antarctic ice melt.

## Claims

- The number of occupied chinstrap penguin nests on Zavodovski Island fell by 63% between 2011 and 2025. (reported by 10 sources)
- Zavodovski Island has lost more than half a million chinstrap penguins. (reported by 10 sources)
- Ocean warming is causing krill to move toward more southern regions, affecting penguin food sources. (reported by 9 sources)
- Norman Ratcliffe of the British Antarctic Survey described the penguin population decline as a massive collapse. (reported by 5 sources)
- A study published in Current Biology documented the penguin population decline. (reported by 5 sources)
- The British Antarctic Survey conducted the research on Zavodovski Island. (reported by 4 sources)
- The 2016 eruption of Mount Curry was not the primary cause of the chinstrap penguin decline. (reported by 3 sources)
- Penguin guano fertilizes green algae, which darkens snow and accelerates melting in Antarctica. (reported by 2 sources)

## Timeline

### 2026-10-09: Zavodovski Island loses status as world's largest penguin colony

Zavodovski Island has lost its title as the world’s largest penguin colony after a 63% decline in chinstrap penguin nests, a crash scientists attribute to climate disruption.

4 sources. https://clstr.news/cluster/zavodovski-island-loses-status-as-worlds-largest-penguin-colony

### 2026-10-07: Zavodovski Island penguin population collapses by 63%

The chinstrap penguin population on Zavodovski Island has plummeted by 63% since 2011, losing over half a million birds due to ocean warming and shifting krill availability.

17 sources. https://clstr.news/cluster/antarctic-penguins-linked-to-accelerated-ice-melt-and-population-declines

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Cite as: Zavodovski Island penguin population decline. CLSTR, https://clstr.news/situations/zavodovski-island-penguin-population-decline