South Australia Declares H5 Escalation After 1,000 Terns Die as Virus Spreads Inland
Updated
Updated · The Guardian · Aug 21
South Australia Declares H5 Escalation After 1,000 Terns Die as Virus Spreads Inland
3 articles · Updated · The Guardian · Aug 21
Summary
More than 1,000 greater crested terns were found dead in three South Australian mass mortality events on Troubridge and the Pages islands, the biggest suspected H5 toll detected on mainland Australia since June.
Aerial surveillance also picked up new tern cases at Flagstaff Hill, McLaren Vale, North Haven, Lucky Bay and Tanunda, plus South Australia's first confirmed raven case at Port MacDonnell, indicating spread from the coast inland.
Authorities are investigating a suspected little penguin case on Kangaroo Island and said no poultry, livestock or mammal mass deaths have been detected so far, though sea lions and fur seals are under watch.
South Australia is preparing targeted vaccination for captive native species including little penguins and orange-bellied parrots, while ruling out broad vaccination of wild birds as impractical.
The outbreak is widening nationally: New South Wales confirmed H5 in 7 birds on the south coast, and Tasmania is testing 28 dead little penguins and 3 crested terns found on King Island.
In August 2026, the highly contagious H5N1 bird flu virus, introduced to Australia by migratory wild birds from the Southern Ocean, quickly spread to all six states and began circulating within local bird populations. Mass deaths were first seen among greater crested terns in South Australia, with the virus soon reaching Tasmania and causing further wildlife losses. Ground-nesting birds like terns and gulls, which nest closely together, proved especially vulnerable, while species such as little penguins benefited from natural social distancing in burrows. Australia's native species, lacking prior exposure to similar viruses, face a high risk of severe decline or extinction as the outbreak continues.