Australia last month became the final continent to confirm a mainland case of H5N1, although the virus had been detected in late 2025 on the sub-Antarctic territory of Heard Island, about 4100km from continental Australia.
Six infections have now been confirmed across three states, including in a seabird called the giant petrel found near the seaside town of Hawks Nest in NSW, Australia's most populous state, the authorities said late on Saturday.
The H5 strain has led to the culling of hundreds of millions of birds in the past few years, disrupting food supplies and driving up prices. Human infections of the virus remain rare.
"The positive test is the first confirmed detection of H5 in New South Wales," state Agriculture Minister Tara Moriarty said in a statement.
There is "no evidence of spread to local wildlife and H5 bird flu has not been detected in commercial poultry flocks, captive birds or any other birds in New South Wales", Moriarty said. "There is no impact on the supply of chicken meat or eggs and I would encourage everyone to purchase these products as they normally would."
The state government has launched a response plan that includes bolstered surveillance operations and the deployment of extra staff to support industry, she said.
Authorities in Australia have ramped up surveillance and testing of wildlife and livestock since the avian flu hit the mainland, with Prime Minister Anthony Albanese pledging his Labor government to do all it can to curb any spread of the virus.
