Scientists report that a bird flu outbreak caused mass death among southern elephant seal pups on Australia’s sub-Antarctic Heard Island. Multiple outlets, drawing on study findings and reporting by Australian Antarctic Program scientists, say the deaths involve the H5N1 virus and affect a breeding colony there. BBC, ABC Australia, Phys.org, and The Guardian all cite testing confirming H5N1 spread among wildlife on the island, with the highest reported toll being more than 13,000 seal pups. BBC and The West Australian also state the mortality rate is more than 75% of the pup population. Observations and surveys are described as taking place during 2025 and early 2026, including drone and ground work, after which researchers finalise the findings from voyages to Heard and McDonald islands. Additional Australian outlets and summaries also reference that thousands of pups may have died across two Antarctic Australian islands, though the most specific figures in the reporting focus on Heard Island. The reports collectively describe a large-scale, ongoing mass-casualty event linked to the H5N1 strain.