A greater crested tern found dead in South Australia has tested positive for the deadly H5 strain of bird flu, the first time the disease has been detected in a local Australian seabird. The discovery represents an escalation of the virus's arrival in the country, according to experts.
Discovery and Confirmation
The dead bird was discovered by a member of the public at Robe Marina on the Limestone Coast on Tuesday, according to the South Australian government. It was collected for testing the same day and results confirmed the presence of H5 bird flu on Friday. Federal Agriculture Minister Julie Collins announced the finding, stating that while concerning, it was not unexpected and demonstrated the effectiveness of Australia's biosecurity system.
Separately, tests on a young fur seal found at Blue Bay on the New South Wales Central Coast returned negative for H5 bird flu on Friday night. The seal died on Thursday, and tests were conducted as a precaution, the NSW government said.
Shift from Migratory to Local Wildlife
Until this detection, all previous Australian cases of H5 bird flu had been in migratory subantarctic seabirds, primarily giant petrels, found along the coasts of South Australia, Western Australia, and New South Wales. Chris Purnell, wetland and migratory shorebird program manager at BirdLife Australia, described the new case as a “paradigm shift” in the disease's progression in Australia. “All previous confirmed detections had been in migratory birds that had likely brought the disease from the subantarctic, but the greater crested tern is an Australian resident seabird,” he said. “Those earlier detections were like little spot fires, but this suggests transmission has occurred on or near our beaches. We consider this to be a local transmission point.”
Risks to Other Species
Greater crested terns live in large mixed flocks with other species, which could facilitate further spread. The location near a network of coastal lakes with many birds adds to concerns. BirdLife Australia is particularly worried about the eastern hooded plover, a vulnerable species whose populations live close to where the tern was found. Purnell noted that terns globally have been heavily affected by H5 bird flu; in France, hundreds of sandwich terns died within days of the first reports.
Jack Gough, chief executive of the Invasive Species Council, said international experience shows H5 can spread quickly and over greater distances than expected. “This is a very serious moment because it’s the first time we’ve seen local transmission of the virus rather than sick pelagic seabirds arriving on the beaches from the Southern Ocean,” he said. “I’m concerned that if we get persistent spread to Australian wildlife, this could quickly turn up all over the Australian continent.”
Response and Surveillance
The South Australian government is leading the response, conducting extra surveillance to determine if the virus has spread further in local wildlife. Earlier this week, the government completed the largest aerial survey of the state’s coastline, islands, and reefs in 40 years, finding “no widespread evidence of sick or dead seabirds or seals.” Collins said the greater crested tern is a coastal seabird with an overlapping range with migratory birds that previously tested positive for H5.
Environment groups view the development as a possible turning point. The Invasive Species Council and BirdLife Australia emphasize the need for heightened vigilance and rapid response to prevent widespread wildlife mortality.
