H5N1 bird flu kills more than 50 skuas in first Antarctica wildlife die off
More than 50 skuas died in Antarctica during the summers of 2023 and 2024 after becoming infected with the
More than 50 skuas died in Antarctica during the summers of 2023 and 2024 after becoming infected with the highly pathogenic avian influenza virus H5N1. Researchers say this marks the first confirmed wildlife die off from the virus on the continent. The findings come from a study led by Erasmus MC in The Netherlands and the University of California, Davis, recently published in Scientific Reports.
Skuas are large brown seabirds related to gulls that live mainly in polar and subpolar regions. They are predators and scavengers, similar in some ways to birds of prey, and play an important role in cleaning up carcasses. That scavenging behavior may also increase their risk of catching and spreading the virus across Antarctica, according to the researchers.
Earlier in 2024, scientists detected H5N1 in a kelp gull and two skuas that were found dead in January and February. However, until now, it had not been proven that the virus was the actual cause of death.
“We knew there were animals with the infection, but this is the first study to show they died of the viral infection,” said co-senior author Ralph Vanstreels, a wildlife veterinarian with the UC Davis One Health Institute within the Weill School of Veterinary Medicine. “It’s an important distinction in the early days of an outbreak.”
Antarctic Expedition Investigates Bird Flu
In March 2024, the research team traveled to Antarctica shortly after the breeding season for skuas and penguins. They examined wildlife at 10 sites across the South Shetland Islands, the northern Weddell Sea, and the Antarctic Peninsula.
Whenever they encountered sick or dead animals, the scientists collected tissue and environmental samples and conducted necropsies to determine the cause of death. They examined the remains of gentoo penguins, Adélie penguins, and Antarctic fur seals, but H5N1 was not identified as the cause in those species.
“As the expedition progressed, it became obvious quickly that skuas were a major victim,” said Vanstreels.
The virus was detected in skuas at three locations: Hope Bay, Devil Island, and Beak Island. Beak Island experienced a large die off of south polar skuas.
“We diagnosed high pathogenicity avian influenza as the cause of death for nearly all of the dead skuas we found at Beak Island,” said first author Matteo Iervolino, a Ph.D. candidate at Erasmus MC in Rotterdam, The Netherlands. “There, I could really see with my eyes the impact this virus can have on these populations.”
Vanstreels described the situation as a “crisis in animal suffering.” H5N1 attacks the brain, leading to severe neurological symptoms such as twisted necks and unusual body stretching. Infected birds may walk or swim in circles, crash into objects, or even fall out of the air. The researchers stress that human activity played a role in the emergence of the virus and is also key to limiting its spread.
How H5N1 Spread Across the Globe
The H5N1 virus was first identified in 1996 on a domestic goose farm in Southeast China. It circulated unchecked in poultry for several years, eventually spilling into wild bird populations. From there, it spread across Europe, the Middle East, and Africa, then to North and South America, and by early 2024, to Antarctica.
The same strain now affecting Antarctic skuas previously caused massive losses among elephant seals and sea lions in Argentina. It has led to the deaths of more than 400 million poultry worldwide and has infected dairy cows, mink, foxes, bears, otters, and many other mammals and wild birds.
H5N1 can also infect humans. Of the roughly 1,000 reported human cases, about half have been fatal.
“We let the virus slip out through our fingers when it first emerged in the poultry industry,” said corresponding senior author Thijs Kuiken, a professor at Erasmus MC. “Once it got into wild bird populations, we lost ability to control this virus. Now it’s established in wild bird populations in all the continental regions of the world except Oceania.”
Calls for Increased Surveillance in Antarctica
Antarctic wildlife already face serious challenges, including climate change, growing tourism, invasive species, overfishing, and pollution. The arrival of avian influenza adds yet another pressure. The study emphasizes the need for stronger surveillance and monitoring to reduce the risk of further spread.
One complication is the lack of recent population data. The last census of Antarctic skuas took place in the 1980s, when researchers estimated about 800 breeding pairs. Without updated numbers, it is difficult to measure how significant the loss of 50 birds may be.
“Everything points toward this virus spreading further,” Kuiken said. “If nobody is watching, we won’t know what is happening.”
The HPAI Australis Expedition was funded by the International Association of Antarctica Tour Operators (IAATO) and Ocean Expeditions. The study was supported by the European Union, Consejo Superior de Investigaciones Científicas (CSIC), and PTI Global Health.
