Avian flu has reached the Antarctic, raising concerns for isolated populations of penguins and seals that have never been exposed to the deadly H5N1 virus before. The full impact of the virus’s arrival is not yet known, but scientists are raising concerns about possible “catastrophic breeding failure” of the region’s fragile wildlife populations. The virus was found in populations of a scavenging bird called brown skua on Bird Island, which is part of the British overseas territory of South Georgia and the South Sandwich Islands. These migratory birds probably brought it with them from South America where bird flu is widespread and has already killed an estimated 500,000 seabirds and 20,000 sea lions in Chile and Peru alone. The current outbreak of the highly infectious variant of H5N1 – which started in 2021 – is estimated to have killed millions of wild birds. Researchers have long been concerned about its potential impact on Antarctic wildlife, because many species are found nowhere else in the world, and are not known to have been exposed to bird flu viruses before. Researchers from the British Antarctic Survey (BAS) took swabs of the birds when they found unexplained mortality and sent them for testing in the UK. Ashley Bennison, the BAS science manager for Bird Island, said: “This is a particularly sad event to confirm. We will continue to monitor the species on the island as best as we can and keep the science going, but we are unsure of the full impact at the moment.” Bird Island is considered one of the planet’s richest wildlife sites, home to many endangered bird species as well as 50,000 pairs of breeding penguins and 65,000 pairs of fur seals. The island lies just off the north-west tip of South Georgia, about 600 miles south-east of the Falkland Islands. A risk assessment on the impacts of bird flu reaching the continent, published by Scientific Committee on Antarctic Research, said fur seals, sea lions, skuas and gulls were the most at risk, followed by penguins, birds of prey, sheathbills and giant petrels. Dr Meagan Dewar, the chair of the Antarctic Wildlife Health Network – who was the lead author of the report – said that the disease could result in “catastrophic breeding failure” in the region, with a “devastating impact on many wildlife species”. The report states that “ongoing disease surveillance programmes should be established to identify new and emerging pathogens”. H5N1 spread almost 4,000 miles down South America in the space of three months, facilitated by migration routes of wild birds. The fact it had already spread down South America made it likely it would arrive in South Georgia at some point, researchers say. As a result of the positive tests on Bird Island, most field work that involves animal handling has been suspended. Staff will have to be extra vigilant about ensuring they have clean clothing and field equipment. The news follows recent research that showed some seabirds in the UK – where the outbreak was first reported – are starting to show immunity to H5N1.