Australia detects first mainland H5 bird flu case as virus completes global spread to all continents

First mainland detection

A brown skua, a migratory seabird, was found dead on a beach inside Cape Le Grand National Park in Western Australia and tested positive for the highly contagious H5 bird flu variant, Agriculture Minister Julie Collins announced in Canberra on Saturday. The result was confirmed by the national science agency. Samples from a second bird, a giant petrel found exhausted in the same area, also returned a presumptive positive.

“Whilst disappointing, this is not unexpected, given the global spread of the H5 bird flu.”

The case marks the first time the H5N1 strain has been confirmed on the Australian mainland, about 700 km (430 miles) south-east of Perth. Collins said there was no evidence of mass bird mortalities and no infections detected in poultry.

A global milestone

Australia had been the last continent without the mainland presence of this deadly strain. The virus had been circulating worldwide since 2021, reaching the sub-Antarctic Australian territory of Heard and McDonald Islands in October 2025, but the mainland had remained free until now.

“This is something that has happened through migratory birds, and has happened by definition around the world, and this is why we are preparing for this.”

The Prime Minister called the detection concerning, but stressed the government would act to contain any spread. Scientists believe the virus was likely introduced to the region by birds migrating from French sub-Antarctic islands.

Preparedness and emergency response

Australia spent years readying itself for an incursion. Biosecurity at farms was tightened, shore birds were being tested, vulnerable species were vaccinated, and response plans were rehearsed. On Saturday, the national emergency animal disease committee convened to coordinate a nationwide reaction.

“I can confirm there is still no evidence of any mass mortalities at this time, nor is there any evidence of infection in any poultry.”

Chief Veterinary Officer Beth Cookson said authorities had been preparing for this moment for a long time, while the Threatened Species Commissioner indicated it would be a few days before they knew if the virus had spread to other animal populations.

Heard Island seal colony devastated

Just days before the mainland confirmation, a scientific study revealed the H5N1 strain had killed more than 13,000 elephant seal pups on Heard Island since August 2025, over 75 percent of the breeding colony of around 17,000 animals. Researchers also recorded higher-than-expected deaths among penguin populations on the remote volcanic archipelago in the southern Indian Ocean.

Killed by H5N113,000

Survived (est.)4,000

Killed by H5N1

13000

Survived (est.)

4000

Data from the article text

Unique wildlife at risk

Wildlife experts warn that an outbreak on the Australian continent could be catastrophic for endemic fauna. Nearly half the country's wild bird species and 83 percent of its mammals are found nowhere else.

“This strain of bird flu has caused huge die-offs of birds and sea mammals. My concerns are that if the H5N1 avian flu virus is confirmed, it will pose a huge risk to some of our more endangered shorebirds, some of our coastal raptors, and our precious, unique, endemic and endangered Australian sea lions, whose population is precarious.”

The H5 strain has already caused severe illness and high death rates in poultry, wild birds and marine mammals globally, with spillovers into cats, goats, alpacas and pigs. Human cases remain rare, but experts fear extensive circulation could lead to mutations enabling human-to-human transmission.