Two sick seabirds discovered near Esperance in Western Australia have brought bird flu to the last continent that had remained free of the disease.

Tests confirmed both birds carried the highly pathogenic avian influenza (HPAI) H5N1 virus, specifically the clade 2.3.4.4b strain known for its rapid global spread.

The infected brown skua and giant petrel are species common in the Southern Ocean, where they travel vast distances across connected ecosystems.

These detections mark the first time this strain has been identified in Australia, following years of global outbreaks that have devastated wild bird populations and poultry operations worldwide.

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Officials caution that it is still unclear whether the Australian cases are isolated incidents or the early sign of broader spread. The coming weeks are expected to reveal more about the severity of the situation.

Since 2021, HPAI H5N1 has reached every continent except Australia until now. Its arrival follows large-scale mortality events among birds and mammals overseas, along with major economic losses in poultry production.

Unlike previous outbreaks in Australia, this strain poses a particular challenge because it infects a wider range of species and moves more easily between animals and continents.

Transmission occurs through close contact or exposure to contaminated environments and carcasses. This makes colony-nesting birds such as gannets, terns, and albatrosses particularly vulnerable, while scavengers like Tasmanian devils could also face elevated risk.

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Health authorities emphasize that the threat to humans remains low. Human infections have been rare and generally occur only after direct or indirect contact with infected animals or contaminated sites such as dairy farms or beaches where sick seabirds or marine mammals appear.

Researchers say the infected seabird species offer clues about how the virus arrived. Brown skuas and giant petrels are long-distance fliers capable of traveling across entire ocean basins, often scavenging dead marine life that can harbor the virus.

Their presence in Western Australia suggests the virus may have reached the mainland via Southern Ocean migration routes from regions like South America rather than through northern shorebird pathways. Genetic sequencing will clarify which route the virus took by comparing it to known strains from Heard Island, Antarctica, and South America.

While the disease has decimated the poultry and dairy industries in the United States, Australia’s agricultural sector has not yet reported any domestic H5N1 infections. Even so, authorities have urged poultry producers to maintain strict biosecurity by minimizing contact between domestic and wild birds, protecting feed and water, and promptly reporting unusual illness or deaths.

Wildlife populations across Australia are now a major focus for monitoring efforts. Fur seals, terns, gannets, albatrosses, and Tasmania’s shy albatross and yula – or short-tailed shearwater – are of particular concern due to their colony-based behavior.

Freshwater species such as ducks could also contribute to the virus’s spread through waterways, endangering rare and endangered birds including the orange-bellied parrot.

Australia’s advantage lies in preparation. Having remained H5N1-free until now allowed authorities to ready a national response led by the National Emergency Management Agency alongside the agriculture, environment, and health departments.

The taskforce has conducted outbreak simulations and expanded testing nationwide. Current advice calls for stepped-up surveillance among seabirds, scavengers, wetlands, marine mammals, and poultry settings, with positive samples to be sequenced quickly to track viral movement.

Planning for wildlife protection is considered critical before species are exposed. In the United States, researchers have even begun testing bird flu vaccines in seals to protect endangered Hawaiian monk seals, an approach that could serve as a model if Australia’s situation worsens.

Authorities are urging the public to help contain the virus. Anyone encountering sick or dead birds or marine mammals should report them to the Emergency Animal Disease Hotline at 1800 675 888, noting the location and taking photos from a safe distance.

People are also advised not to touch dead or sick animals and to keep pets, especially dogs, away from carcasses to reduce risk of transmission.

According to Jane Younger, Senior Lecturer in Southern Ocean Vertebrate Ecology at the University of Tasmania’s Institute for Marine and Antarctic Studies, the next phase will depend on how effectively early detections are managed and whether the virus establishes itself in Australia’s unique wildlife.