{ "abstract": "High pathogenicity avian influenza (HPAI) has spread across the sub-Antarctic, causing significant wildlife impacts. We report its first detection in an Australian external territory, Heard Island and McDonald Islands, which supports over one million breeding seabirds and seals. Drone and ground surveys (October 2025, January 2026), combined with viral genome analysis, confirmed infection with Influenza A H5N1 clade 2.3.4.4b at Heard Island. Drone surveys revealed mass mortality in southern elephant seals, with 8,573 pups (62%) recorded dead across Heard Island by the final surveys. Mortality increased at an average rate of 5.6% per day in a subset of harems, and the highest observed mortality in a harem was 97%. Based on the average (76%) mortality in the final surveys, total estimated pup mortality at Heard Island was 13,359 (from a total population of 17,364 pups), though this may be an underestimate as mortality was ongoing at this time. HPAI was detected in six of nine species tested and, we suspect, led to elevated mortality in king and gentoo penguins. Phylogenetic analysis indicates the virus was introduced from Crozet Islands, with an estimated arrival around August 2025. These data show the continued easterly spread of HPAI around the sub-Antarctic, with severe but heterogeneous impacts across taxa. Our results demonstrate the value of drones for large-scale monitoring, underscoring the need for continued and enhanced HPAI surveillance across the Southern Ocean.", "abstract_shown": true, "affiliations": [ "Australian Antarctic Division, Department of Climate Change, Energy, the Environment and Water, Kingston, Tasmania 7050, Australia", "Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Hobart 7004, Australia", "Center for Wildlife Studies, Camden, ME 04843 USA", "School of Infectious Diseases and Global Health, Tufts University’s Cummings School of Veterinary Medicine North Grafton, MA, 01536, USA", "IMOS Animal Tagging, Sydney Institute of Marine Science, 19 Chowder Bay Road, Mosman, 2088, New South Wales, Australia", "Australian Centre for Disease Preparedness, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Geelong, VIC 3220, Australia", "Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), CNRS, Université Montpellier, EPHE, IRD, Montpellier, France", "ANSES, Ploufragan-Plouzané-Niort Laboratory, National Reference Laboratory for Avian Influenza, Unité de virologie, Immunologie, Parasitologie, Aviaires et Cunicoles, Ploufragan, France", "Department of Microbiology, Immunology and Transplantation, Rega Institute, KU Leuven, Leuven, Belgium" ], "article_type": null, "arxiv": null, "author_total": 21, "authors": [ { "affs": [ 0, 1 ], "name": "Julie C. McInnes", "orcid": "0000-0001-8902-5199" }, { "affs": [ 0, 2, 3 ], "name": "Tristan L. Burgess", "orcid": "0000-0002-9457-9150" }, { "affs": [ 0, 1 ], "name": "Georgia Mergard", "orcid": "0000-0002-3121-8833" }, { "affs": [ 0 ], "name": "Melanie R. Wells", "orcid": "0000-0003-2817-8743" }, { "affs": [ 4 ], "name": "Clive R. McMahon", "orcid": "0000-0001-5241-8917" }, { "affs": [ 5 ], "name": "Matthew J. Neave", "orcid": "0000-0002-8108-0553" }, { "affs": [ 0 ], "name": "Andrea Maree Polanowski", "orcid": "0000-0002-9612-220X" }, { "affs": [ 0 ], "name": "Aleks Terauds", "orcid": "0000-0001-7804-6648" }, { "affs": [ 6 ], "name": "J Tornos", "orcid": "0000-0002-8793-2518" }, { "affs": [ 6 ], "name": "Mathilde Lejeune", "orcid": "0009-0004-3153-7203" }, { "affs": [ 7 ], "name": "François‐Xavier Briand", "orcid": "0000-0002-8094-9368" }, { "affs": [ 8 ], "name": "Guy Baele", "orcid": "0000-0002-1915-7732" }, { "affs": [ 6 ], "name": "Thierry Boulinier", "orcid": "0000-0002-5898-7667" }, { "affs": [ 0 ], "name": "Helen Achurch", "orcid": "0009-0008-8238-3936" }, { "affs": [ 0 ], "name": "Rachael L. Alderman" }, { "affs": [ 0 ], "name": "Anna Lashko" }, { "affs": [ 0 ], "name": "Barbara C. Wienecke", "orcid": "0000-0002-1505-164X" }, { "affs": [ 0 ], "name": "Louise P. Wynen", "orcid": "0009-0001-1112-1591" }, { "affs": [ 0 ], "name": "Benjamin M. Viola", "orcid": "0000-0003-2620-2914" }, { "affs": [ 0, 1 ], "name": "Patti Virtue", "orcid": "0000-0002-9870-1256" }, { "affs": [ 0 ], "name": "Jarrod C. Hodgson", "orcid": "0000-0003-0481-7360" } ], "bibtex": "https://research.draconitic.com/paper/9g6xavrxjw12t.bib", "cited_by": 10, "doi": "10.64898/2026.06.16.732752", "fulltext_url": null, "id": "9g6xavrxjw12t", "issns": [], "landing_url": "https://doi.org/10.64898/2026.06.16.732752", "language": "en", "licence": "CC-BY-NC-ND", "licence_label": "CC BY-NC-ND", "licence_source": "journal", "licence_url": "https://creativecommons.org/licenses/by-nc-nd/4.0/", "metadata_licence": null, "native_subjects": [ [ "openalex", "2713|Influenza Virus Research Studies" ] ], "openalex": "W7165038861", "pdf_url": "https://www.biorxiv.org/content/biorxiv/early/2026/06/17/2026.06.16.732752.full.pdf", "pmcid": null, "pmid": null, "published": "2026-06-17", "publisher": "Cold Spring Harbor Laboratory", "ris": "https://research.draconitic.com/paper/9g6xavrxjw12t.ris", "sources": [ { "first_seen": "2026-10-30T13:26:56Z", "native_id": "W7165038861", "source": "openalex", "url": "https://doi.org/10.64898/2026.06.16.732752" } ], "subjects": [ { "field": "medicine", "origin": "openalex:2713|Influenza Virus Research Studies", "subfield": "epidemiology-public-health" } ], "title": "Mass mortality of southern elephant seals during multi-species outbreak of HPAI H5N1 on sub-Antarctic Heard Island", "title_text": "Mass mortality of southern elephant seals during multi-species outbreak of HPAI H5N1 on sub-Antarctic Heard Island", "type": "preprint", "updated_at": "2026-11-04T13:21:15Z", "url": "https://research.draconitic.com/paper/9g6xavrxjw12t", "venue": "bioRxiv (Cold Spring Harbor Laboratory)", "versions": [] }