A highly pathogenic avian influenza (H5N1) is suspected of killing over 75% of southern elephant seal pups on the remote Heard and McDonald Islands, a subantarctic Australian territory. Researchers estimate more than 13,000 pups died out of a population of 17,000 between October and January. Mortality rates reached as high as 97% in some areas of the islands, which are a crucial breeding ground for millions of birds and seals. This marks the first detection of avian influenza in an Australian external territory, indicating its spread around the sub-Antarctic region. The virus was detected in six animal species, including elephant seals, king and macaroni penguins, and other seabirds. Scientists used drones and on-the-ground surveys to collect samples, and are continuing to investigate the outbreak, noting unexpectedly high penguin mortality as well. The findings are currently published on BioRxiv and await peer review.