Massive Seal Pup Mortality Linked to H5N1 Bird Flu
Recent scientific findings reveal that thousands of southern elephant seal pups on Australia's distant Antarctic islands have succumbed to bird flu. Heard and McDonald Islands, situated approximately 4,000 km southwest of Australia, are vital breeding grounds for over a million seabirds and seals.
High Mortality Rates Among Seal Pups and Penguins
Data collected between October and January suggests that an estimated 13,000 out of 17,000 baby seals on Heard Island, representing more than 75% of the group, have died from the H5N1 strain of bird flu since last August. The study also noted an increase in deaths within penguin populations beyond expected levels. While H5N1 has spread globally among avian species and affected some mammals, Australia has remained free of the strain on its mainland.
This preliminary research, published in BioRxiv and awaiting peer review, utilized drone surveys and on-ground visits to these inaccessible islands. Scientists gathered samples from nine species, with six testing positive for the H5N1 strain. These included southern elephant seals, king and gentoo penguins, Antarctic fur seals, and South Georgia diving petrels.
“These observations of H5 bird flu at Heard Island and McDonald Island are the first detection in an Australian external territory and show the continued eastward movement of the virus around the sub-Antarctic,” stated lead author and wildlife biologist Dr. Julie McInnes. “Our results show a similar pattern to other sub-Antarctic islands, such as South Georgia, where elephant seals have been hardest hit.”
The initial alert about bird flu's potential impact on the islands came late last year when a research expedition discovered numerous deceased baby seals. Subsequent investigations in January confirmed that the H5N1 strain primarily affected southern elephant seal pup populations, with a lesser but notable impact on king and gentoo penguins. The report estimates 13,359 deaths among a population of 17,364 seal pups on Heard Island, exceeding 75% of the total. Researchers believe this mortality rate might be an underestimate, as pups were still dying during the final surveys. In one specific area, 97% of baby seals perished. While several hundred adult king penguins also died, this represented a low proportion of their overall population but was still above normal levels.
Broader Implications and Ongoing Monitoring
The study found no unusual mortality rates among the albatross population or two endemic species, the Heard Island shad and the black-faced sheathbill. Australian Environment Minister Murray Watt described the seal deaths as “sobering,” emphasizing the need for Australia to remain vigilant and prepare for the potential arrival of the strain on the mainland. He stressed that a realistic outlook on an incursion is necessary for appropriate planning.
Scientists hypothesize that the bird flu was likely introduced to the islands last August by migratory birds from the French-owned Crozet Islands, located approximately 1,800 km away. The Australian Antarctic Program, a collaborative effort between government and research institutions, will continue to monitor its territories for further signs of bird flu.
Source: Bird flu kills more than 75% of baby seals on remote Australian island, study finds