What we know about the birds infected with deadly bird flu and where they fly

Avian influenza has been detected several times in brown skuas on subantarctic islands. (Bettina Arrigoni, Brown Skua, CC BY 2.0 DEED) A second migratory seabird, a giant petrel, found washed up in Western Australia has tested positive for the H5N1 bird flu. Fifty-eight dead or sick birds found in WA over the weekend have been reported and nine samples collected for testing. An expert wildlife advisory group has been put together to provide information on the movements and locations in Australia that other members of the infected seabird species could visit. Link copiedShareShare articleEnhanced bird flu surveillance of Australia's southern coast will focus on the movements of two migratory seabirds species that have tested positive for the deadly virus. A second bird, a giant petrel, was today confirmed to have a strain of avian influenza known as H5N1 2.3.4.4b, which has killed millions of birds and mammals around the world. The bird was found washed up near Esperance, WA, after a brown skua that also had the virus was found in the same area on June 14. Over recent years avian influenza has made its way across the globe. Now Australia has its first case. Here's what we know. Both species spend some of the year on subantarctic islands — with the closest islands known to have bird flu some 4,500 kilometres away — and can winter in waters off Australia from WA to Queensland. Australia's chief veterinary officer Beth Cookson said an expert wildlife advisory group had been formed to provide information on the movement and locations of the two seabird species in terms of where they were likely to co-mingle with other animals. "That will help inform the enhanced surveillance approach that we'll take to determine whether this is spread further," she said. Initially, Australian authorities were concerned the virus would come from the north during the annual migration of migratory shorebirds between September and March. That is because ducks and migratory shorebirds have been key spreaders of the virus in other parts of the world over long distances. But the detection of H5N1 on Kerguelen Islands in October 2024, and Heard Island and McDonald Islands in October 2025 indicated spread from the south was another viable route of transmission. Genomic sequencing is still underway to determine the virus's route into Australia and whether it came directly from subantarctic islands to the south-west of the country. Ducks and shorebirds were key species in the spread the virus around Europe, Asia, Africa and the Americas since 2020. But the two species of birds detected with the virus in Australia — brown skua and giant petrel — have been implicated in the spread of bird flu from South America and into the Antarctic region across the Southern Ocean. Research director Christophe Barbraud, from the marine predator team at the French National Centre for Scientific Research, said that was because of the birds' feeding habits, ecology and large-scale movements. Birds become infected through the transfer of mucous, saliva, faeces or eating infected carcasses. Brown skuas are opportunistic scavengers and also steal food from other animals in a habit known as kleptoparasitism. (iNaturalist: Simon Plat, Brown skua, CC BY-NC 4.0) Marcel Klaassen, an ecologist at Deakin University, said skuas could also get the virus from birds they stole food from. "When they see a bird has good food, a big crop, they follow them until they throw it up and eat it," Professor Klaassen said. Dead skuas have been a common species sampled by researchers throughout the Antarctic region in the past few years. A brown skua found on an Australian beach was confirmed to be infected with a highly pathogenic strain of avian influenza. (iNaturalist: Oscar Thomas, Brown skua, CC BY-NC 4.0) During winter skuas and giant petrels that live on subantarctic islands disperse throughout the Indian, Atlantic and Pacific Oceans, including to waters off Australia. It takes about a month, give or take a week, for a skua to travel from the closest subantarctic islands to Western Australia. Past studies of skuas that live on Kerguelen Island, near Heard Island, have shown individual birds will fly to offshore areas of Australia all along its southern coastline for the winter. What is unclear is how long skuas and giant petrels can survive with the virus or how long it takes to incubate in them. Generally, these migratory seabirds stay offshore when they come near Australia, as they can roost on the water. "They rarely make it to our shores," Professor Klaassen said. Seabird ecologist Yuna Kim, the seabird project coordinator for Birdlife Australia, said skuas were understudied. "A lot of penguins get researched because people love penguins, but skuas, because they take penguin chicks, they are not loved by people," she said. "But we need to pay attention to these high-risk birds. Their populations are under threat with this disease and they can

What we know about the birds infected with deadly bird flu and where they fly

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What we know about the birds infected with deadly bird flu and where they fly

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