Avian Cholera Found to Kill Antarctic Penguins
International investigators determined a bacterial disease, not H5N1 avian influenza, caused a 2024 die-off of seabirds on Antarctica's Danger Islands.
Updated on Nov. 5, 2026 in Bird Watching
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Investigators determined that avian cholera, not H5N1 avian influenza, caused a mass mortality of Adélie penguins and other seabirds on the Danger Islands, Antarctica, in March 2024. Samples from 49 carcasses pointed to the disease as the cause of death for most animals examined.
Why it matters
The findings rule out H5N1 as the driver of this die-off and show that the bacterial strain has circulated in Antarctica for more than two decades. For bird watchers and wildlife observers, the results highlight that seabird colonies in the region can face disease threats that were already present well before the 2024 event.
Researchers analyzed tissue samples and swabs from 49 carcasses and performed genetic analyses on the bacterial strain responsible for the outbreak. The strain has circulated in Antarctica for more than two decades, but the report does not say how it arrived or whether it will cause further die-offs.
The details
Mass mortality of Adélie penguins and other seabirds was documented on the Danger Islands in March 2024, and investigators initially considered H5N1 avian influenza. Testing of tissue samples and swabs collected from the carcasses established avian cholera as the cause for the majority of animals examined.
Timeline
March 2024: Mass mortality of seabirds recorded on the Danger Islands, Antarctica.
More than two decades before 2024: The bacterial strain began circulating in Antarctica.
Seasonal Patterns
The genetic analyses showing the avian cholera strain has persisted in Antarctica for over two decades extend existing surveillance of Antarctic seabird colonies. The finding indicates the disease was already present in the region before the March 2024 mortality event.
Bird watchers who visit or follow Antarctic seabird colonies may find that some species are affected by disease that has persisted for years. Observers should be aware that sightings of sick or dead birds in such areas could relate to this established pathogen.
The takeaway
Disease can persist unnoticed in remote wildlife populations for many years before a die-off reveals it. Keeping records of unusual bird mortality helps researchers distinguish between newly introduced threats and long-standing ones.
Further reading
For more on wild bird populations and how disease affects them, explore Bird Watching.
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Should governments spend more on monitoring wildlife diseases in remote regions like Antarctica?
