In more and more parts of the Antarctic, birds on the bird flu virus H5N1. South Georgia and James Ross Island are no longer affected, but now also King George Island, as the latest findings show. The unusually high number of dead animals there also suggests that a highly contagious variant of the aggressive influenza virus is currently circulating. The researchers therefore fear considerable long -term consequences for the bird populations in the Antarctic.
The H5N1 bird flu virus has spread from Asia since 2021. It has also reached some of the most remote places, including the predominantly isolated wildlife populations in the Antarctic. Since then, more and more parts of the Antarctic have been haunted by the aggressive tribe of this influenza virus: In October 2023, researchers showed this H5N1 variant for the first time in sick skuas (robbery) in the South Atlantic, at that time on the subantarctic island of South Georgia. The pathogen was probably introduced there by migratory birds from South America. Shortly afterwards, in February 2024, they also found birds on James Ross Island. This island is much further south and close to the mainland of Antarctic.
Unusually large number of dead birds on King George Island
A team around Christina Braun from the University of Jena has now examined other bird stocks in Antarctica for the virus. Her long-term monitoring comprises a 35 square kilometer area around a research station on the Fildes Peninsula on King George Island, not far from the Antarctic mainland. 14 breeding bird species are regularly observed, including reins, adélie and donkey spenguins as well as skuas and giant storm birds.
During their latest expedition in January and February 2025, the researchers now found H5N1 viruses in samples of infected birds for the first time. In total, Braun and her colleagues watched 52 dead animals within the short brood season 2025, mostly Skuas. Usually you will find only a few dead animals during this period, as you explain. This suggests that a highly pathogenic variant of H5N1 is currently circulating there.
Does H5N1 continue to spread?
The research team fears that this virus will continue to spread in the breeding area of Antarctic. It is advantageous for the pathogen that the birds often breed there in a very small and cramped area. Because only about two percent of the Antarctic area are ice -free, the birds all frolic in the same region. “In addition, the Antarctic birds breed typically in colonies. That is why the risk of infection is very great,” explains Markus Bernhardt-Römermann from the University of Jena.
Another problem: Unlike a flu in humans, the current bird flu is almost 100 percent fatal. So if such a colony is infected with the H5N1 virus and most animals die, the serious consequences for the entire population can have. “If the mortality rate is very high, it may be that the population collapses completely,” says Bernhardt-Römermann.
As elsewhere, the Antarctic also always has the risk that the virus will be transferred to mammals and also causes severe to fatal waves in these populations. In Chile, Peru and Argentina, H5N1 jumped on seals, sea lions and sea elephants, for example, and led to a mass extinction on the coasts there in 2023. “Individual infections in people after direct contact with infected birds are also documented,” says Braun. Your team therefore wore protective clothing. So far, however, there are no signs that bird flu can be passed on from person to person. Anyone who is infected usually only develops a temporary respiratory disease.
Birds in Antarctic also react to climate change
In addition to bird flu, the team on King George Island observed another worrying trend: “The species composition shifts rapidly”, explain the researchers and blame climate change. For example, the Cape Storm birds, which brooded hundreds on the island a few years ago, have now disappeared completely. The populations of the adélie and reinspengination are also shrunk. The researchers, on the other hand, recorded an increase in the giant storm birds and the donkeys. Both bird species have so far preferred subantarctic, warmer regions. But with climate change they seem to continue to go to the mainland.
From November, researchers will explore whether the bird flu actually spreads and how this and climatic warming affect the Antarctic fauna in November in their next Antarctic expedition.
Source: Friedrich-Schiller-Universität Jena