Skip to content
DraconiticResearch
Search Sources API
203,234 studies31 sourcesUpdated 7 min ago
PreprintCC BY-NC-NDbioRxiv (Cold Spring Harbor Laboratory)

Mass mortality of southern elephant seals during multi-species outbreak of HPAI H5N1 on sub-Antarctic Heard Island

  • Julie C. McInnes1,2
  • Tristan L. Burgess1,3,4
  • Georgia Mergard1,2
  • Melanie R. Wells1
  • Clive R. McMahon5
  • Matthew J. Neave6
  • Andrea Maree Polanowski1
  • Aleks Terauds1
  • J Tornos7
  • Mathilde Lejeune7
  • François‐Xavier Briand8
  • Guy Baele9
9 more authors
  • Thierry Boulinier7
  • Helen Achurch1
  • Rachael L. Alderman1
  • Anna Lashko1
  • Barbara C. Wienecke1
  • Louise P. Wynen1
  • Benjamin M. Viola1
  • Patti Virtue1,2
  • Jarrod C. Hodgson1
9 affiliations
  1. 1Australian Antarctic Division, Department of Climate Change, Energy, the Environment and Water, Kingston, Tasmania 7050, Australia
  2. 2Institute for Marine and Antarctic Studies, University of Tasmania, Battery Point, Hobart 7004, Australia
  3. 3Center for Wildlife Studies, Camden, ME 04843 USA
  4. 4School of Infectious Diseases and Global Health, Tufts University’s Cummings School of Veterinary Medicine North Grafton, MA, 01536, USA
  5. 5IMOS Animal Tagging, Sydney Institute of Marine Science, 19 Chowder Bay Road, Mosman, 2088, New South Wales, Australia
  6. 6Australian Centre for Disease Preparedness, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Geelong, VIC 3220, Australia
  7. 7Centre d’Ecologie Fonctionnelle et Evolutive (CEFE), CNRS, Université Montpellier, EPHE, IRD, Montpellier, France
  8. 8ANSES, Ploufragan-Plouzané-Niort Laboratory, National Reference Laboratory for Avian Influenza, Unité de virologie, Immunologie, Parasitologie, Aviaires et Cunicoles, Ploufragan, France
  9. 9Department of Microbiology, Immunology and Transplantation, Rega Institute, KU Leuven, Leuven, Belgium
Open at sourcePDFDOICite

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.

Related

  1. Beyond viral species: the increasing mortality burden of the ongoing Bundibugyo ebolavirus outbreak in the Democratic Republic of the Congo
    Justin Kambale Kahingi, Relindis Mpembe Ngila, Roland Muhindo Muyisa
    Infectious MedicinePeer-reviewedCC BY-NC-ND 4.0Full textInfectious diseasePMC
  2. Open ecological, genomic and digital behavioural data resolve the 2026 MV Hondius Andes virus outbreak to the southern-Andean reservoir zone
    D. Redding, G. Albaladejo-Robles, J. G. Nino Barreat +2
    medRxivPreprintCC BYFull textEpidemiology & public healthmedRxiv
  3. Hepatitis A outbreak response in a vulnerable setting: lessons from southern Portugal
    EA Matias, IF Medeiros, IC Gonçalves +5
    The European Journal of Public HealthPeer-reviewedCC BY-NC 4.0Full textGeneral medicinePMCEurope PMC
  4. Progress but not on track: forecasting under-five mortality and the likelihood of achieving SDG target 3.2 in Southern Africa
    Welcome J. Dlamini, Thabo Lephoto
    BMC Public HealthPeer-reviewedCC BY 4.0Epidemiology & public healthCrossref
  5. Survival Status and Predictors of Mortality Among Women With Breast Cancer in Southern Ethiopia: A Retrospective Cohort Study
    Bitsiet Desta, Tsion Zebdiwos Chema, Sophonias Sisay +2
    Cancer reports (Hoboken, N.J.)Peer-reviewedCC BYFull textGeneral medicineEurope PMC

Cite

BibTeXRIS
BibTeX
@misc{mcinnes2026mass,
  title = {{Mass mortality of southern elephant seals during multi-species outbreak of HPAI H5N1 on sub-Antarctic Heard Island}},
  author = {Julie C. McInnes and Tristan L. Burgess and Georgia Mergard and Melanie R. Wells and Clive R. McMahon and Matthew J. Neave and Andrea Maree Polanowski and Aleks Terauds and J Tornos and Mathilde Lejeune and François‐Xavier Briand and Guy Baele and Thierry Boulinier and Helen Achurch and Rachael L. Alderman and Anna Lashko and Barbara C. Wienecke and Louise P. Wynen and Benjamin M. Viola and Patti Virtue and Jarrod C. Hodgson},
  howpublished = {bioRxiv (Cold Spring Harbor Laboratory)},
  year = {2026},
  month = jun,
  doi = {10.64898/2026.06.16.732752},
  url = {https://doi.org/10.64898/2026.06.16.732752},
  note = {CC BY-NC-ND},
}
RIS
TY  - UNPB
TI  - Mass mortality of southern elephant seals during multi-species outbreak of HPAI H5N1 on sub-Antarctic Heard Island
AU  - Julie C. McInnes
AU  - Tristan L. Burgess
AU  - Georgia Mergard
AU  - Melanie R. Wells
AU  - Clive R. McMahon
AU  - Matthew J. Neave
AU  - Andrea Maree Polanowski
AU  - Aleks Terauds
AU  - J Tornos
AU  - Mathilde Lejeune
AU  - François‐Xavier Briand
AU  - Guy Baele
AU  - Thierry Boulinier
AU  - Helen Achurch
AU  - Rachael L. Alderman
AU  - Anna Lashko
AU  - Barbara C. Wienecke
AU  - Louise P. Wynen
AU  - Benjamin M. Viola
AU  - Patti Virtue
AU  - Jarrod C. Hodgson
PY  - 2026
DA  - 2026/06/17
PB  - bioRxiv (Cold Spring Harbor Laboratory)
DO  - 10.64898/2026.06.16.732752
UR  - https://doi.org/10.64898/2026.06.16.732752
AB  - 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.
ER  -