More than 13,000 seal pups die on remote Australian island amid bird flu outbreak

Over 13,000 southern elephant seal pups have died on Australia's remote Heard Island due to the H5N1 bird flu virus. Government scientists observed the mass mortality during drone and ground surveys in October 2025 and January 2026, with death rates reaching up to 97% in some areas, significantly higher than the typical below 5% mortality. Testing confirmed the virus has spread to multiple species, including penguins and other seals, on Heard and McDonald Islands. Genetic analysis suggests the virus likely arrived from the French Crozet Islands. This marks the first detection of H5N1 in an Australian external territory, prompting the Australian government to allocate additional funds for preparedness against potential mainland incursions.

Scientists have documented a significant mortality event among southern elephant seal pups on Australia's remote Heard Island. Research based on data from October and January indicates that the H5N1 strain of bird flu killed approximately 13,000 pups, representing over 75% of the observed group of 17,000. This outbreak, which began around August, also led to higher-than-expected deaths in penguin populations. Samples collected from nine species on Heard and McDonald Islands revealed the H5N1 strain in six, including southern elephant seals, king and gentoo penguins, Antarctic fur seals, and South George diving petrels. The findings, published in BioRxiv, emerged after scientists were alerted by a research voyage that discovered hundreds of dead seal pups late last year.