A long-nosed fur seal found dead at Beachport on Wednesday on the Limestone Coast of South Australia has tested positive for the H5 strain of avian influenza, marking the first confirmed case in a mammal on the Australian mainland. Federal Agriculture Minister Julie Collins announced the discovery during a media conference in Hobart, noting that the animal was found approximately 300 kilometres south of Adelaide.
Australia Confirms First H5 Bird Flu Death in a Mainland Mammal
This is sadly our first confirmed case of H5 bird flu in a mammal in Australia,
Ms Collins said, speaking to reporters in Hobart.
Although this is a concerning development, it is not unexpected for us to start to see infection in other wildlife, particularly in marine mammals, particularly in areas where there are high infection rates in wild birds,
Ms Collins said. “I have been advised that at this time the detection does not appear to be associated with other sick or dead marine mammals. An infection of this individual animal is likely to have occurred due to exposure to infected wild birds or the environment that they share.”
The SA government has also confirmed a little penguin found at Kangaroo Island this week also tested positive for H5 bird flu. Long-nosed fur seals and the endangered Australian sea lion are among the mammal species the federal government has assessed as facing very high risk from the virus.
Escalating Wildlife Mortalities Across Offshore Islands and Mainland Coastlines
The seal’s death marks a fresh escalation in the spread of the virus days after South Australian Premier Peter Malinauskas announced three mass mortality events on offshore islands involving more than 1,000 greater crested terns. The outbreak was confirmed after dozens of greater crested terns and silver gulls died at Baudin Rocks, off Cape Jaffa in South Australia, becoming Australia’s first recorded mass mortality event linked to the H5 strain of bird flu.
Authorities said aerial surveillance over Baudin Rocks detected about 50 dead birds and another 30 showing signs of illness, with laboratory testing later confirming H5 infection in five greater crested terns and one silver gull.
Concerns have rapidly expanded beyond South Australia after aerial surveillance identified another cluster of sick and dead greater crested terns in Victoria’s Glenelg River estuary near Nelson and at nearby Lawrence Rocks. Victorian authorities are awaiting laboratory confirmation, but officials said field observations closely resemble the South Australian outbreak, which would become Australia’s second documented mass mortality event linked to the virus if confirmed.
Victorian Chief Biodiversity Officer James Todd said surveillance findings were consistent with the recent outbreak across the border. State Chief Veterinary Officer Graeme Cooke also reported a clear increase in dead seabirds along Victoria’s southwest coastline during recent inspections.
Beyond South Australia’s initial outbreak, authorities have confirmed 18 additional H5 cases across several new locations, including Pages Islands, Troubridge Island, Southend, Glenelg, Monarto, and the internationally significant Coorong wetlands. South Australian Environment Minister Emily Bourke said the expanding geographic spread demonstrates how quickly the virus is moving beyond seabird colonies, with the detection in a migratory petrel at the Coorong heightening concerns because the wetland supports large populations of native waterbirds and migratory species.
The National Toll and Scientific Tracking Across States
Nationwide tracking by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) has confirmed 74 H5 bird flu cases nationwide, with detections reported across South Australia, Victoria, Western Australia, New South Wales, and Queensland. There have now been 298 positive H5 bird flu events recorded in Australia since the outbreak, with 183 of those in South Australia.
Despite the widespread detections, Ms Collins stated, At this stage there is no evidence of infection in our poultry or agriculture systems.
Government Warnings of a Prolonged Environmental Challenge
Federal and state leaders are warning that more mass bird deaths are likely as the country confirmed its first large-scale wildlife mortality event caused by the highly pathogenic H5 avian influenza virus, marking what officials described as the beginning of a prolonged environmental crisis. Agriculture Minister Julie Collins said the virus could continue affecting Australia’s wildlife for years despite extensive preparedness efforts.
This could be a long period of time and a very long journey,
Ms Collins said, noting that countries overseas have been battling the same strain since 2022. She added that Australia had done everything possible to delay the virus’ arrival, but acknowledged it was impossible to stop such a highly contagious disease from spreading among wild birds.
We've certainly seen devastating impacts overseas, particularly mass bird mortalities,
Ms Collins said. We cannot stop a very virulent, very contagious disease in wild birds.
She added, This is not something that will disappear quickly. Australians should expect further spread and larger numbers of wildlife to be affected.
Environment Minister Murray Watt issued an equally stark warning, saying Australians should prepare for further wildlife losses. I want to level with people: this is the beginning of what is likely to be a long, difficult journey in terms of the impacts on wildlife,
Mr Watt said.
Mr Watt said Australia had been the last continent to record the arrival of this particular H5 strain, allowing authorities additional time to prepare, but once the virus entered migratory bird populations, preventing further spread became virtually impossible. The reality is, you can't stop native and wild birds flying around, and you can't stop wild animals moving around,
Mr Watt said. That will mean more mass mortality events like the one we have now seen.
The Australian government said eradication is no longer considered feasible and efforts will instead focus on monitoring outbreaks, protecting vulnerable wildlife populations where possible, and strengthening surveillance across affected regions.
Public Safety Measures and What Remains Unresolved
Federal Agriculture Minister Julie Collins urged anyone who sees sick or dead birds not to touch them or get close to them but to record their location and make a report.
While Victorian authorities await laboratory confirmation for the Glenelg River estuary and Lawrence Rocks clusters, the exact timeline for how the virus will further impact additional mainland mammal populations remains unconfirmed.
