A study and related reporting say bird flu caused large-scale death among seal pups on subantarctic Heard Island, a remote Australian territory. Multiple outlets report that more than 13,000 southern elephant seal pups have died, with one study estimating mortality above 75% among baby seals. The deaths are attributed to infection with the H5N1 strain. The Guardian and others describe confirmatory testing that finds the virus is present and spreading among wildlife on the island, including penguins, seals and petrels. Observations were made during government-led surveys using drone and ground methods in October 2025 and January 2026, according to The Guardian. Other outlets focus on the scale of the die-off and the ongoing nature of the mass-casualty event. Some reports mention the impact across two Antarctic Australian islands, while the core finding across the coverage is that H5N1 is driving extensive mortality in seal pups on Heard Island.