A deadly strain of bird flu spreading across remote islands near Antarctica has devastated native wildlife populations, killing an estimated 13,000 seal pups as well as penguins and seabirds, researchers say.
Drone surveys by the Australian Antarctic Program in October and January revealed “devastating” images of baby seal carcasses strewn across the greyish volcanic shores of Heard and McDonald Islands, said Jarrod Hodgson, a senior research scientist at the organisation.
The islands, located about 4,000 kilometers southwest of mainland Australia, have long been an isolated sanctuary for breeding birds and marine mammals.
According to the program, southern elephant seal pup mortality was estimated at 76 percent in a population of 17,000 pups born on the islands. In one particular area, the mortality rate was concentrated at 97%.
“What we don’t know from our studies so far is what the impact was on the adult breeding population of southern elephant seals,” Hodgson said.
Data collected in January also revealed that several hundred adult king penguins on Heard Island have died, with scientists noting mortality was above normal levels.
“These observations of H5 avian flu on Heard Island and McDonald Island represent the first detection in an Australian external territory and demonstrate the continued eastward movement of the virus in the subantarctic zone,” said wildlife biologist Julie McInnes.
“Our results show a similar pattern to other subantarctic islands, such as South Georgia, where elephant seals have been most affected,” added McInnes, who is also the lead author of the group’s study.
As of February, neither mainland Australia nor New Zealand had recorded cases of the H5N1 strain, which has spread among birds around the world and affected some mammals.
Analysis of genetic data suggests that H5 bird flu likely reached the islands via wildlife from the French subantarctic Crozet Islands, 1,800 km away, and likely occurred around August 2025.
The results have been published in the scientific journal BioRxiv, but have not yet been peer-reviewed.
