H5 Bird Flu Detected in Elephant Seal and Gull on Macquarie Island

Official testing confirmed the highly pathogenic H5 bird flu strain in samples collected from a southern elephant seal and a kelp gull on Macquarie Island, marking the first time the virus has been detected on the sub-Antarctic territory. The World Heritage-listed wildlife sanctuary sits in the Southern Ocean approximately 1,500 kilometres south-east of Hobart, serving as a critical breeding ground for up to 100,000 seals and 4 million seabirds.

Key Clinical Takeaways:
• H5 avian influenza has been officially confirmed in a southern elephant seal and a kelp gull on Macquarie Island, representing the first detection of the virus in a marine mammal in Tasmania.
• Federal Agriculture Minister Julie Collins stated that samples from three other bird species—skuas, giant petrels, and penguins—returned negative test results, with no mass mortality events observed among the island wildlife at this stage.
• The Australian Antarctic Division previously planned to withdraw personnel from the remote research station due to the psychological risk posed by a potential outbreak among vulnerable animal populations.

H5 Strain Kills Thousands of Baby Seals

Macquarie Island follows the late 2025 detection of the virus on Heard Island, another sub-Antarctic Australian territory where more than 13,000 baby seals died from the infection. Southern elephant seals, which can weigh up to 3,600 kilograms, demonstrate high susceptibility to the H5 strain. Federal government data indicates that pup mortality rates in vulnerable populations can exceed 90 percent.

Tasmania’s Minister for the Environment and Climate Change, Guy Barnett, noted in a statement that the finding is the first recorded case of the virus in a marine mammal within the state. Samples were collected by island personnel and returned to the mainland for diagnostic testing.

Authorities Test Multiple Bird Species for Pathogen

Federal Agriculture Minister Julie Collins told parliament that additional biological samples collected from skuas, giant petrels, and penguins tested negative for the pathogen. The positive samples taken from the southern elephant seal and kelp gull are scheduled for further examination at a CSIRO laboratory to characterize the viral load and lineage.

State and federal authorities continue broad surveillance across the region. Tasmania recorded 50 separate bird flu events, encompassing multi-species detections including a Pacific gull at St Helens, a greater crested tern at Bridport, a little penguin at Cooee, and a black currawong on Flinders Island. Officials confirmed zero detections in commercial poultry flocks or backyard setups across the state.

Personnel Leave Macquarie Island to Avoid Wildlife Fatalities

In August, Australia’s environment department announced plans to withdraw personnel from the Macquarie Island research station. Expert assessments predicted the virus would likely trigger a significant mortality event during the seasonal breeding aggregation of elephant seals, creating severe psychological risks for expeditioners witnessing widespread wildlife fatalities.

Independent Southern Ocean marine mammal expert Mary-Anne Lea noted that high-density breeding aggregations create conditions where transmission risks remain elevated, although widespread outbreaks are not automatically guaranteed at every site. State environment authorities urge the public to avoid handling sick or dead wildlife and to report potential sightings through the Tasmanian Department of Natural Resources and Environment reporting portal or by calling the Emergency Animal Disease Hotline.

Disclaimer: The information provided in this article is for educational and scientific communication purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider regarding any medical condition, diagnosis, or treatment plan.