Australia's run as the only continent free of the deadly H5 bird flu virus has ended, with the federal agriculture minister, Julie Collins, confirming that a brown skua found sick in Western Australia died from the H5N1 strain. A second bird, a giant petrel found nearby, also tested positive for the virus, marking the first mainland cases of the highly pathogenic avian influenza.
What is H5 Bird Flu and Why Are Authorities Concerned?
H5 bird flu is a highly pathogenic virus that is highly contagious and causes serious illness, including death in animals. Dr Ariful Islam, a veterinary epidemiologist at Charles Sturt University, describes it as a 'panzootic' that has spread across multiple continents and affected many species. According to Wildlife Health Australia, more than 560 wild bird species and over 100 mammal species have been infected globally.
Where Did It Come From?
The deadly H5N1 clade 2.3.4.4b strain originated in Asia and has been spreading globally since 2021, reaching Antarctica during the 2023-24 summer. Australian researchers estimate it arrived on Heard Island, an Australian territory about 4,000 km southwest of Perth, in August 2025, killing over 13,000 southern elephant seal pups and hundreds of king penguins.
How Did It Arrive on the Australian Mainland?
The brown skua, a subantarctic species, was found sick at Cape Le Grand National Park near Esperance on 14 June and subsequently died. An initial positive test was later confirmed by the CSIRO's Australian Centre for Disease Preparedness. A second bird, a giant petrel from the same area, tested positive at a WA government laboratory, pending further confirmation. The two birds likely migrated from the subantarctic, according to BirdLife Australia.
What Does It Mean for Australian Agriculture?
This H5 strain differs from the H7 bird flu that caused outbreaks in poultry farms across several Australian states in 2024 and 2025, leading to the culling of hundreds of thousands of chickens. Dr Michelle Wille, an avian influenza expert at the University of Melbourne, notes that in the US, more than 200 million chickens have been culled since the virus arrived, impacting farmers and consumers. The virus has also led to human infections, primarily among poultry workers.
What Are the Risks for Human Health?
The Australian Centre for Disease Control states that bird flu infections in people are rare and often mild but can cause severe disease or death. Symptoms include fever, cough, sore throat, conjunctivitis, and muscle aches. Dr Matt Mason from the University of the Sunshine Coast says the risk to the general public remains low, with limited evidence of human-to-human transmission. From 2003 to early 2026, the WHO reported 997 human cases of H5 infection from 25 countries, with 478 fatalities.
What Are the Risks to Native Wildlife?
Dr Fiona Fraser, Australia's threatened species commissioner, warns that if H5 bird flu becomes established in wildlife, there is little that can be done to stop its spread. At-risk species include the Tasmanian devil, the critically endangered orange-bellied parrot, and the Australian fur seal. Authorities have developed over 100 response plans for vulnerable animals and important sites. Jack Gough, CEO of the Invasive Species Council, calls the arrival a 'genuine wildlife emergency' and urges emergency funding. The Australian Marine Conservation Society fears the virus poses a 'real extinction risk' for the endangered Australian sea lion, with only 12,000 remaining.
What to Do If You See Sick Birds or Marine Mammals?
The public is urged to avoid contact with dead or sick birds or animals showing signs of bird flu and to report sightings to the emergency animal disease hotline at 1800 675 888 or birdflu.gov.au.
