Suspected bird flu threatens sea lion breeding grounds in South Australia

Mass bird deaths believed to be linked to H5N1 bird flu have been detected on islands that host one of Australia's largest sea lion breeding colonies. The deaths were reported on the Pages Islands, off South Australia, where the endangered Australian sea lion breeds alongside large numbers of seabirds. Authorities have not detected the virus in Australian sea lions in the country so far, but the finding has raised concern because the disease has already spread to marine mammals in other parts of the world.

Sponsored

The South Australian government said on Thursday that the Pages Islands were the site of one of three mass bird death events it had revealed. About 1,000 birds, mostly greater crested terns, were found dead there. Testing results are still pending, so officials have not yet confirmed that the birds were infected with H5N1.

The same report also said bird flu had been detected at Seal Bay, another important South Australian location for sea lions. The Australian sea lion is listed as endangered on international threatened species lists, with its total population estimated at fewer than 10,000. Around 85% of the population is in South Australia and the remaining 15% in Western Australia.

That concentration makes the species vulnerable to disease outbreaks at key breeding sites, especially if a virus reaches colonies where animals gather closely during breeding seasons. The government is considering a vaccination program, drawing on a rollout used for seals in Hawaii. The concern is heightened by the way H5 bird flu has behaved elsewhere.

Sponsored

The virus has already jumped species in South America and Antarctica, affecting pinnipeds such as seals and sea lions. A University of Sydney veterinarian, Rachael Gray, said she had seen the impact firsthand in the sub-Antarctic region in late 2023 and described it as sobering. She said later research had shown reduced numbers returning to breed in subsequent years, underlining the possible longer-term effects of the disease on wildlife populations.

The Pages Islands are described as one of the largest and most stable sea lion colonies. Their location, between Kangaroo Island and the South Australian mainland, makes them a significant breeding ground for the species. Any spread of bird flu to sea lions there would be a major conservation concern because the colony is part of a small and geographically concentrated population.

The situation also matters for biosecurity planning, as authorities weigh whether preventive vaccination could reduce the risk to wildlife before any confirmed spillover occurs. What remains unclear is whether the dead birds on the Pages Islands are confirmed to have H5N1 and whether the virus has reached sea lions in Australia. Officials are still awaiting test results, and the scale of any wider spread is not yet known.

#birdflu #H5N1 #Australiansealion #SouthAustralia #biosecurity

Sponsored