Testing at CSIRO’s Australian Centre for Disease Preparedness has identified the virus in a giant petrel found in Western Australia.
Australian Chief Veterinary Officer Dr Beth Cookson said the latest detection brought the national tally to four confirmed cases in wild migratory seabirds, two previous in Western Australia, one in South Australia, and now this most recent find.
Another suspected positive detection has also been reported in Western Australia, in a giant petrel discovered at Roses Beach, west of Esperance.
Samples have been sent to CSIRO for confirmatory testing.
Dr Cookson emphasised detections remained confined to vagrant migratory seabirds that occasionally visit southern Australia.
There is currently no evidence of mass mortality events and no detections in poultry or the broader agricultural production system.
The risk to human health remains low.
H5 bird flu is considered the most serious strain of avian influenza.
While it primarily affects wild and domestic birds, it can also infect some mammals, and has caused significant animal losses globally.
Impacts can extend to food supply, the environment and the economy.
Authorities are urging the public to remain vigilant.
Anyone who spots multiple sick or dead birds or other animals is advised not to touch them, record what they observe, including date, time and location, and report to the Emergency Animal Disease Hotline on 1800 675 888.