Australia has confirmed its first mass-mortality event of wild birds caused by H5N1 avian influenza [1, 2].

This development marks a significant escalation in the spread of the highly pathogenic virus among native seabirds. The event signals a shift from isolated cases to rapid, large-scale die-offs that could threaten local biodiversity and wildlife populations.

Authorities identified more than 80 dead greater crested terns on the island of Baudin Rocks, located on the south-east coast of South Australia near Cape Jaffa [2, 3]. Testing for the dead birds began on Aug. 1 and subsequently confirmed the H5N1 infection [1, 2].

According to the South Australian Department for Environment and Water, this is the first mass-mortality event linked to H5 bird flu in the country [3]. The virus has spread across several regions, with a total of 74 reported cases nationwide [1].

South Australia has seen the highest impact with 54 cases [1]. Western Australia reported 10 cases, while Victoria recorded seven [1]. New South Wales and Queensland reported two and one cases, respectively [1].

Agriculture Minister Julie Collins said the government is closely monitoring the situation and working with states and territories to manage the response [1]. The effort involves coordination between CSIRO scientists and South Australian authorities to track the virus's movement.

A CSIRO spokesperson said testing of the dead birds at Baudin Rocks confirmed the H5N1 infection [2]. The rapid nature of the die-off highlights the virulence of the strain within native avian populations, a concern for environmental agencies across the continent.

“More than 80 greater crested terns have been found dead on the island”

The transition from sporadic individual infections to a mass-mortality event indicates that H5N1 has established a more aggressive transmission pattern within Australia's wild bird populations. With South Australia emerging as a primary hotspot, the focus now shifts to containment and monitoring to prevent the virus from jumping to poultry populations or other vulnerable wildlife species.