Australia on Saturday confirmed its first case of H5N1 bird flu on the sub-Antarctic Macquarie Island, with the deadly virus found in the remote territory’s vulnerable elephant seal population.
Australia’s Chief Veterinary Officer Beth Cookson said official testing confirmed the highly pathogenic virus strain “in samples collected from an elephant seal and a kelp gull on Macquarie Island, marking the first H5 event on this island”.
Australia in June became the last continent to report bird flu, although the virus was detected in late 2025 on another of its sub-Antarctic territories, Heard Island, where more than 13,000 baby seals were killed by the virus, according to local media.
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Like Heard Island, Macquarie Island, a UNESCO World Heritage-listed territory located in the Southern Ocean halfway between Australia’s Tasmania state and Antarctica, is a key breeding ground for southern elephant seals.
The mammals, which can weigh up to 3,600 kg (7,936 pounds), are particularly susceptible to H5 bird flu, with pup mortality rates in some cases of more than 90%, according to the federal government.
In August, Australia’s environment department said it would withdraw personnel from a research station on Macquarie Island due to the “psycho-social risk to expeditioners of a potential H5 avian influenza outbreak”.
Expert assessments predicted the virus would likely cause a significant elephant seal mortality event during the upcoming breeding season, the environment department said.
