The lethal form of bird flu that has been killing millions of wild birds around the world has spread south to the Antarctic region, where it is feared it will have a devastating impact on seals and whales as well as birds such as penguins and albatrosses. It could even lead to extinctions.
“There are species on some of the Antarctic islands and sub-Antarctic islands that are unique to those islands, and only occur in small numbers, in hundreds or thousands,” says Thijs Kuiken at Erasmus University Rotterdam in the Netherlands. “If the virus reaches those populations, they are in threat of extinction.”
If the virus spreads around Antarctica, there is also a risk of migratory birds carrying it to New Zealand and Australia for the first time, says Kuiken.
The highly pathogenic form of H5N1 bird flu that has been killing many wild birds in Europe, Asia and Africa since 2020 was carried across the Atlantic to North America in 2021. In October 2022, it was detected in South America.
There it is known to have killed thousands of marine mammals as well as hundreds of thousands of birds of many different species, and the true numbers are likely to be much higher. By December 2022, it had spread to the southern tip of South America.
In recent days, researchers at a British Antarctic Survey station on Bird Island, just off the larger island of South Georgia, found some sick brown skuas and giant petrels, and sent samples back to the UK for testing.
“The test came back yesterday, and they were indeed positive,” says Norman Ratcliffe, a seabird ecologist at the British Antarctic Survey.
So far, only 30 dead birds have been found, but the fear is that H5N1 could spread rapidly in the large and dense bird colonies on Bird Island and South Georgia.
Skuas and giant petrels will kill or scavenge other birds, making them particularly likely to get infected. They also winter off the coast of South America and migrate to places like South Georgia for the summer, says Ratcliffe. So it was thought that these birds are the species likely to spread the disease in the Antarctic region.
Animals in the Antarctic have never been exposed to highly pathogenic bird flu before, but “there is a real chance that the virus will reach, or has already reached, the mainland of Antarctica”, says Kuiken, one of the authors of an August report warning of the risk of highly pathogenic bird flu reaching Antarctica.
There are only a few stations on the mainland, and the tourist season hasn’t yet begun, so Antarctic birds could already be dying without being noticed, says Ratcliffe. “There’s very little observation going on there.”
Birds such as penguins and albatrosses are slow breeders, says Kuiken. “So if there is mortality in a breeding colony of, let’s say, 50 or 70 per cent, as we have seen in some seabird colonies in Europe, then it will take years, if not decades, for these populations to return to their previous levels.”
Rare species at risk from the virus include several species of parakeet found only on the Auckland and Antipodes islands south of New Zealand, the flightless Falkland steamer duck, the Kerguelen tern and the New Zealand sea lion, according to the August report.
Antarctic researchers are taking precautions such as disinfecting footwear and equipment, and sites where the disease is present will be closed to tourism, but other than that there isn’t much that can be done to stop the spread of the virus. “It’s most likely that transmission will be bird to bird,” says Ratcliffe.
The viruses from Bird Island are now being sequenced, says Ian Brown at the UK’s Animal and Plant Health Agency, which did the initial testing. “We know it’s H5N1 but further characterisation is under way, including genomics, which will confirm the relationship to other viruses and therefore likely origins,” he says.