Thousands of Dead Adélie Penguins Found on Danger Islands
Thousands of dead Adélie penguins litter the snow on the Danger Islands in the Weddell Sea, surrounded by the remains of skuas, snowy sheathbills, a fur seal, and a giant petrel. Researchers working on the archipelago in early 2024 initially suspected the mass mortality was caused by highly pathogenic avian influenza (H5N1). The virus had recently reached Antarctica, killing birds on South Georgia Island.
Bacterial Infection Trumps Avian Influenza Suspicions
Laboratory tests of 49 dead animals revealed a different pathogen entirely. According to molecular tests and autopsies, 46 of the 49 samples contained the DNA of Pasteurella multocida, the bacterium responsible for avian cholera. Influenza virus was present in only a few individuals and at minimal concentrations. Microscopy confirmed characteristic tissue necrosis and bacterial accumulations in the livers and blood vessels of the birds, explaining an infection that can kill within hours without outward symptoms.
Decades-Old Bacterial Strain Strikes Stable Colony
Genetic analysis established that the Pasteurella multocida strain found on the Danger Islands is almost identical to a strain that struck penguins in Hope Bay in 2001. The findings indicate the pathogen has circulated in Southern Ocean waters for at least two decades. While populations along the western Antarctic Peninsula decline, the Danger Islands hold about 55 percent of the peninsula’s Adélie penguin breeding population. Researchers estimate that roughly one percent of adult birds died on Heroine Island alone, though heavy snowfall and scavengers likely obscure the true toll.
Frequently Asked Questions About the Antarctic Outbreak
How many Adélie penguins live on the Danger Islands?
The archipelago supports approximately one and a half million Adélie penguins, representing about 7.5 percent of the global population and 55 percent of the breeding population on the Antarctic Peninsula.
What other species were found dead alongside the penguins?
Researchers documented the remains of skuas, snowy sheathbills, a giant petrel, and a single fur seal among the bird carcasses on the islands.
When did the outbreak occur on the islands?
Examination of nesting sites indicated that the peak mortality event took place during January and early February 2024.
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