The study’s use of UAV-based mapping marks a major advance in monitoring capacity on the remote island, enabling researchers to gather accurate counts in minutes – work that previously required laborious foot surveys. Harsh conditions, including snow, rain, and gale-force winds, added to the challenge.
“UAVs are allowing us to count large animal populations quickly and safely,” said BAS ecologist and co-author Jamie Coleman. “Despite challenging weather, we were able to collect critical data that helps us understand how these remarkable animals are being affected by their changing environment.”
The findings align closely with recent mass die-offs in South American elephant seal populations, where HPAI has caused mortality exceeding 70% in some regions. Until now, South Georgia’s remote location had been seen as a buffer against such outbreaks.
Sue Gregory, Senior Marine and Fisheries Manager at the Government of South Georgia and the South Sandwich Islands (GSGSSI), said the results – while sobering – are vital to ongoing management efforts.
“Having seen the impact of HPAI on elephant seals in South America, we were braced for similar consequences,” Gregory noted. “This study is a valuable contribution to monitoring how our top predators respond to rapidly changing environmental pressures.”
The research builds on a decade of continuous population monitoring led by BAS, integrating traditional ground counts with UAV surveys and satellite observations. These long-term datasets provide the baseline needed to distinguish temporary disruptions from deeper, sustained population change.
The work was supported by a Biodiversity Challenge Fund Darwin Plus grant (DPLUS214) and carried out under permits issued by the Government of South Georgia and the South Sandwich Islands.
The full study, ‘Highly Pathogenic Avian Influenza Viruses (HPAIV) associated with major southern elephant seal decline at South Georgia’, by Connor Bamford et al., is available in Communications Biology.