With confirmed H5N1 cases exceeding 230 and a mass wildlife mortality event recorded, federal officials have secured 1,500 vaccine vials to protect vulnerable captive native birds.

The detection of H5N1 in silver gulls and greater crested terns suggests a shift from sporadic migratory arrivals to environmental spread across five states.

New South Wales is the third Australian state to detect H5N1 bird flu after finding the virus in a migratory seabird. Officials confirm the risk to the public remains low and poultry supplies are secure.

Agricultural authorities are urging poultry producers to upgrade biosecurity as the highly pathogenic H5N1 virus reaches Australia's east coast and continues to devastate US farms.