Australian authorities on Saturday confirmed the first detection of H5N1 avian influenza on the country’s mainland, found in a migratory brown skua near Esperance in Western Australia. A second seabird, a southern giant petrel, is suspected to be infected. With the confirmation, the highly pathogenic clade 2.3.4.4b virus—responsible for mass die-offs among wild birds and mammals globally—has now reached every continent. No signs of mass mortalities or poultry infections have been reported thus far, according to Agriculture Minister Julie Collins.

Scientists attribute the incursion to migratory birds moving through the Southern Ocean, where the virus has circulated on sub-Antarctic islands. Australia’s external territory of Heard Island recorded heavy losses last year, with an estimated 13,000 elephant seal pups killed. Officials had long anticipated an eventual mainland arrival and convened an emergency animal disease committee on Saturday. Prime Minister Anthony Albanese described the detection as concerning but stressed that preparations were already in place, including enhanced biosecurity and coastal surveillance.

Ecologists across Australian universities warn that the virus poses a particular threat to endemic species. Black swans, which lack certain immune genes found in other waterfowl, could suffer catastrophic declines if the virus enters freshwater systems via ducks. Other at-risk animals include Australian sea lions, orange-bellied parrots, Tasmanian devils, and little penguins. Authorities have activated protection plans for more than 35 vulnerable species, including captive breeding programmes. The poultry industry, especially free-range operations, faces potential housing orders to limit exposure. No human cases have been reported in Australia; globally, human infections remain uncommon and tied to close contact with sick animals.

In the coming days, diagnostic tests will clarify whether the virus has spread beyond the two seabirds. State and federal veterinary services are triaging reports of sick animals along the coast. The national taskforce will coordinate surveillance and industry support. If the virus reaches wild duck populations, officials say the risk profile will change significantly. The public is urged to report dead or ailing birds without handling them. The next critical milestone: confirmation of any domestic poultry incursion or evidence of transmission in freshwater wetlands.