Thousands of southern elephant seal pups on a remote Australian island have succumbed to the H5N1 strain of bird flu, with a new study estimating that over 75% of the local population has died. Heard Island, located approximately 4,000 km south-west of Australia, is a critical breeding ground for over a million seabirds and seals.
Scientists, analysing data collected between last October and this January, believe around 13,000 baby seals from an estimated group of 17,000 on Heard Island have perished due to the H5N1 virus since last August. This represents a devastating mortality rate of more than 75% for the entire group of pups. The research also highlighted higher-than-expected deaths among certain penguin populations.
The study, led by wildlife biologist Dr Julie McInnes and published in the scientific journal BioRxiv, utilised drone surveys and ground visits to these hard-to-reach islands. Researchers collected samples from nine species, with six testing positive for the H5N1 strain. These included the southern elephant seal, king and gentoo penguins, the Antarctic fur seal, and the South Georgia diving petrel. It is important to note that these findings are yet to undergo peer review.
Dr McInnes stated that these observations on Heard and McDonald Islands represent the first detection of H5 bird flu in an Australian external territory, indicating the continued eastward spread of the virus across the sub-Antarctic region. She added that the results mirror patterns seen on other sub-Antarctic islands, such as South Georgia, where elephant seals have been particularly hard hit.
The Australian Antarctic Program, a collaborative effort between government and research institutions, will continue to monitor for signs of bird flu in its territories. Environment Minister Murray Watt described the seal deaths as 'sobering,' emphasising the need for Australia to remain vigilant and prepare for the potential arrival of the strain on the mainland.
Scientists hypothesise that the bird flu was likely introduced to the islands last August by migrating birds originating from the French-owned Crozet Islands, situated approximately 1,800 km away. The report found no unusual deaths among the albatross population or two endemic species, the Heard Island shad and the black-faced sheathbill.