South Australian authorities are investigating a mass mortality event after more than 80 dead and sick greater crested terns were discovered on Baudin Rocks, an island approximately five kilometres south of Cape Jaffa on the state's southeast coast. Testing is underway to confirm whether the birds were infected with the H5 strain of avian influenza, with officials indicating a negative result is considered highly unlikely.

What Was Found on Baudin Rocks

State aerial surveillance conducted on Friday detected 49 dead and 35 sick greater crested terns on the island. South Australia's Chief Veterinary Officer Skye Fruean described it as 'very unlikely' the birds would test negative for H5, though laboratory results remain pending.

The discovery adds to a growing tally: South Australia has now recorded 39 of Australia's 53 confirmed H5 bird flu cases, according to official updates. Australian Chief Veterinary Officer Beth Cookson stated that the risk to agriculture and human health remains low.

Endangered Sea Lions Now in the Crosshairs

The outbreak's reach has extended beyond seabirds, raising urgent concern for the endangered Australian sea lion. One of the Kangaroo Island cases was detected at Seal Bay, which is home to approximately five per cent of the global population of the species.

Wayne Boardman, a wildlife veterinarian from the University of Adelaide, warned that historical precedent from South America makes the jump from birds to sea lions near-inevitable. 'The issue now with bird flu being found on Seal Bay is that it's almost certainly going to go from the birds into the sea lions,' he said.

His concern is grounded in documented evidence: the H5N1 strain killed an estimated 30,000 sea lions in South America within six months in 2022, and an estimated 13,359 southern elephant seal pups on Australia's Heard Island in the Southern Ocean between August 2025 and January 2026.

Government Response and Beach Closures

The South Australian government on Wednesday announced the temporary suspension of beach tours at Seal Bay to protect local sea lion and seal populations. The move reflects growing official concern that the virus could devastate a species already classified as endangered.

Minister for Agriculture, Fisheries and Forestry Julie Collins told reporters on Friday that authorities would continue working with experts to contain the spread. She confirmed there has been no evidence of the virus entering agricultural or poultry systems, and that the threat to human health remains low.

A Seagull First and the Broader Outbreak

Separately, authorities in South Australia reported that Australia's first suspected case of the highly pathogenic strain in a seagull was also detected on the state's southeast coast — another marker of the outbreak's widening geographic and species footprint. This comes amid warnings that the virus, already entrenched across 39 confirmed SA cases, is tracking toward a wildlife crisis with few recent parallels in Australia.

With laboratory results pending and sea lion populations directly in the virus's path, the coming days will be critical in determining the scale of South Australia's H5 bird flu emergency.