A bird on the ice
An Antarctic skua, one of the birds hardest hit by avian flu in the region. Peter Prokosch via Flickr
A deadly strain of H5N1, commonly known as avian flu, has been found in birds across the Antarctic peninsula. Scientists are worried about the devastating impact the virus could have on wildlife.
Between November 2024 and January 2025, a team of researchers travelled along the peninsula with a mobile laboratory and surveyed 16 seabird nesting sites. More than 180 of the 846 samples they collected had the virus. The 188 positive samples came from nine bird and four seal species. “The virus has reached every corner [of the peninsula] and is infecting almost every animal species,” says Antonio Alcamí, a microbiologist who led the expedition, to Sofia Moutinho at Science magazine.
Avian flu has wreaked havoc in other parts of the world. According to the World Organization for Animal Health, the United States, where the virus has severely impacted cattle and poultry, currently has 1028 ongoing outbreaks. In 2023, more than 11,000 animals, including sea lions, penguins and dolphins, died from avian flu in Chile.
Scientists are worried because many of the animals living on the Antarctic peninsula breed in dense colonies, which means the virus could spread at a high rate. “One single island can hold 90 percent of the population of a species,” explains wildlife veterinarian Marcela Uhart to Science.
Skuas are the hardest hit, probably because the migratory seabirds scavenge on corpses. “The reported deaths of skuas is concerning,” says Thijs Kuiken, a pathologist at Erasmus University Rotterdam, to Michael Le Page at the New Scientist. Some species with small populations could be entirely wiped out by the virus, he adds.
Penguins seem to still be faring well. “We have not seen signs of illness in penguins, but we have found the virus in dead animals of many species, and also in live penguins that we are sampling,” Alcamí says to the Spanish newspaper El País. “Although we have not seen symptoms in some penguin colonies, the virus is circulating.”
In fact, Juliana Vianna, one of the scientists on the survey team, tells the New Scientist that the team recently received reports of dead skuas and penguins from the Chilean Antarctic Institute.
Scientists are still figuring out the scope of the virus’ impact and spread. “The situation in Antarctica is a bit of a black box,” says Michelle Wille, a virus ecologist at the University of Melbourne who was not involved in the research, to Science. “We’re still very much in the learning phase, so this new data is really important for us to better understand what is possibly going on.”
The virus has also been detected in the Indian Ocean subantarctic region, on the archipelagos of Crozet and Kerguelen. A pre-print published in late February documented that the virus was likely carried there from South Georgia Island, off the coast of Antarctica. Australian scientists are now on high alert for the virus, which has so far spared the continent.
“This is an example of virus spread across the open ocean, across thousands of kilometers,” says Wille, to Peter de Kruijff at the Australian Broadcasting Corporation. “That demonstrates the ability for the virus to move vast distances.”
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Sara Hashemi | READ MORE
Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.