The deadliest avian influenza virus in history, which has killed millions of birds over the past five years, has jumped back into mammals and wiped out the world’s largest sea elephant, which lives on the remote British-controlled island of South Georgia, about 1,500 kilometers from Antarctica. The British Antarctic Service estimates that more than 50,000 women, the majority of the total, go missing from one year to the next. “The scale of this retreat is staggering,” warned marine ecologist Conor Bamford, the study’s leader.
The virus’s journey probably began in 1996 at Sanshui goose farms in southern China, a humid region plagued by poultry farms that are ideal breeding grounds for the emergence of new pathogens. After several weaker attacks, a new version of the virus, called 2.3.4.4b, emerged in 2020 and began moving across the United States from north to south with a lethality never seen before. Highly pathogenic avian influenza killed 150 million birds in 84 countries in 2022 alone, according to data from the World Animal Health Organization. On September 16, 2023, a group of British scientists discovered a giant, immobile specimen of an Antarctic shearwater (a two-metre-long bird) on Pajaro Island, near southern Georgia. Plague had just arrived at the entrance to Antarctica, the last unexplored continent on Earth.
From there, the virus quickly jumped into mammals. Conor Bamford’s team used drones to count the number of elephant seals in three major colonies in Del Sur state, Georgia. Before the bird flu outbreak, there were about 10,000 birds. After the arrival of the virus, some of it disappeared. Applying these results to the island’s entire population would reduce the number of women by 53,000, a huge blow to the southern sea elephant, which is currently considered a threatened species. A few decades ago, there were about 700,000 copies in existence worldwide, according to the last census.
Spanish virologist Antonio Alcami led an expedition in 2024 and 2025 to measure the impact of bird flu in Antarctica. This year, scientists traveled to the shores of the Antarctic Peninsula, the region of the continent closest to the south of the United States, aboard a sailing ship converted into a laboratory. The virus was ubiquitous, infecting one in four animals analyzed at nearly every site visited. Although penguins were more resistant than feared, the pathogen also infected other birds, including penguins. Following a Spanish expedition, two journalists from EL PAÍS were the first to document the devastation of bird flu in Antarctica.
“Just because we don’t see carcasses of marine mammals doesn’t mean they aren’t dead, because they could be dying in the ocean where we can’t see them,” Alkami argued, trapping his yacht in dangerous Antarctic waters. Now, note that the decline in the number of women in just one year is a “very high number.” This is especially true in some species, where individuals reaching a weight of 4 tons can live for more than 20 years under normal conditions. “This is a significant impact, especially considering that 50% of its reproductive population is found in south Georgia,” warns the virologist at the Institute for Advanced Study (CSIC). A new work was published in a specialized magazine in July this year. communication biology.
Alkami blames the lack of support to analyze the impact of bird flu in Antarctica. “We’re concerned that other species of marine mammals could be similarly affected, but we have no information about what’s going on,” he laments. His mission last year was made possible thanks to a donation of 300,000 euros from Spain’s Union of Acegradras and Reasegradras, as well as logistical support from the CSIC Antarctic base, with financial support from the Ministry of Science. No funding was found this year to continue the investigation. “I’m a little hopeless,” he says.
In October 2023, veterinarian Ralph Vanstrels, a Spanish-Belgian man, witnessed the most harrowing scene of his career on a beach in the protected peninsula of Valdes in Argentine Patagonia. The arena was filled with dying and dead elephant seals, making it difficult to walk. His colleagues calculated that the virus killed about 17,000 people in just a few weeks, killing more than 95% of their descendants. “The new study in south Georgia is very worrying because it’s a very similar pattern to what happened here in Argentina. We suggest that all populations of sea elephants where the virus caused germination are affected to the same level, which is very serious,” said Van Streels, from the University of California, Davis (EE UU). “This is a species that was not in danger of extinction, but suddenly it has declined to the limit. This has very serious implications for the conservation of the species,” Subraya said.
Analysis of the Argentina outbreak raised the alarming possibility that the virus in the soil jumped from birds and was then transmitted from sea elephant to sea elephant. The evolution of infectious and deadly avian influenza viruses within mammalian populations is the scenario most feared by public health experts, as the World Health Organization’s scientific director, British doctor Jeremy Farrar, warned after an outbreak of avian influenza on a mink farm in Galicia in October 2022. However, the agency believes the risk to humans is “low” unless the virus changes and starts spreading among humans.
Ecologist Conor Bamford argues that the pathogen persists within the elephant seal population. His colleagues are reading the virus’s genetic material from different animals to understand how the islands migrated and what mutations occurred along the way. “There was mammal-to-mammal transmission through the air, with contaminated droplets transmitting the virus between hosts. This is probably why sea elephants, which form dense colonies in south Georgia each year, are so severely affected,” said researchers from the British Antarctic Division. Mr Bamford acknowledged that other factors may have contributed to the women’s disappearances, such as some regional climate anomalies, but said natural variation from year to year could be up to 10% and up to 50%. “Decreases like those observed in other countries can only be attributed to highly pathogenic avian influenza,” he says.
Sea elephants are divided into two species, with the majority living in the southern hemisphere and a smaller number living in the northern hemisphere, and so far the virus has had little effect on them. Biologist Michel Ville manages the avian influenza database for the Scientific Committee for Antarctic Research, the international body that coordinates Antarctic science. “Highly pathogenic avian influenza has been devastating for southern elephant seals,” he says. “These mortality rates are shocking, but not surprising, because similar numbers are seen in many species of birds, so the impact is significant,” continued Weale, from the University of Melbourne in Australia. “One might wonder whether this species can survive this situation.”
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