A migratory seabird known as a northern giant petrel found sick on a remote beach tested positive, Agriculture Minister Julie Collins said, after a brown skua case on Saturday.
Both birds were found near the coastal town of Esperance, about 570 kilometres southeast of the state capital of Perth.
“We’re working very closely with both the chicken, meat and the egg poultry system and industries to do everything that we can do and improve biosecurity, and those systems and those areas to stop it from getting into those production systems,” she said.
“Can we do that forever? We don’t know the answer to that, that is a hypothetical.”
Human infections remain rare, but the global spread of avian influenza has devastated flocks, disrupted supplies and pushed up food prices in recent years.
Until now, Australia had been the only continent without a confirmed mainland case, though the virus was detected in late 2025 on the sub-Antarctic territory of Heard Island.
In its efforts to tackle bird flu, Australia has tightened farm biosecurity, increased testing of shorebirds, vaccinated vulnerable species and conducted response simulations.
Poultry producer Inghams said it would move to a complete lockdown as a precaution across all farms and processing sites in Western Australia.
“There has been no detection in commercial poultry, which includes Ingham’s operations and its supply chain,” it said in a statement. (Reuters)