Brown skuas and giant petrels rarely make landfall. When they were found in WA, scientists feared ‘bad news’ for wildlife

Brown Skuas and Giant Petrels Rarely Make Landfall. When They Were Found in WA, Scientists Feared ‘Bad News’ for Wildlife

Brown skuas and giant petrels rarely - Off the coast of southern Australia, Brown skuas and giant petrels are a frequent sight during the winter months, typically observed in their natural foraging grounds. These seabirds are known for their preference to remain at sea, rarely venturing onto land. However, this pattern changed recently when two individuals were discovered unwell on beaches separated by a few kilometers along Western Australia’s southern coastline. The discovery sparked immediate concern among scientists, who feared the potential implications for local wildlife.

The first confirmed case emerged when a giant petrel tested positive for the H5N1 strain of avian influenza, a highly contagious virus that has claimed millions of bird and mammal lives globally since 2021. Two days later, a Brown skua also showed signs of infection, marking the first instances of the disease in Australia. Both birds later succumbed to the illness, adding to the growing list of affected species. This development is particularly alarming because, until now, the virus had not been detected on the continent, leaving its wildlife unprepared for the threat.

Avian influenza, specifically the H5N1 variant, has wreaked havoc on bird populations across the northern hemisphere, where it has spread rapidly through migratory species. Experts previously believed the virus might reach Australia via similar routes, though the timing of its arrival has raised questions about its future impact. Dr Lauren Roman, a seabird researcher at the University of Tasmania’s Institute for Marine and Antarctic Studies, noted that biosecurity teams had been monitoring the northern hemisphere for potential incursions. “We were warned about the possibility of migratory shorebirds and seabirds carrying the virus into Australia,” she explained. “This case suggests the virus has finally made its way to our shores.”

The virus’s journey to Australia could be linked to its seasonal migration patterns. Both Brown skuas and giant petrels breed in Antarctica during the summer months but spend the winter foraging in southern waters, including off the coast of Western Australia. These birds often scavenge for food at sea, and their behavior may have facilitated the spread of the disease across the Southern Hemisphere. Dr Roman highlighted that this practice could explain how the virus traveled from Antarctica to other regions. “If a sick bird dies on the beach, it might be consumed by other species like gulls, which could then carry the infection further,” she said.

Over the past two years, Australian authorities and researchers have conducted extensive surveillance for the H5N1 strain, scanning for any signs of its presence. Despite this vigilance, all tests had returned negative until the recent findings. The discovery of the virus in WA has now triggered a heightened state of alert among conservationists and government agencies. Dr Beth Cookson, Australia’s chief veterinary officer, emphasized that there was no evidence of the disease spreading to other birds yet. “While we are concerned, the current situation shows the virus has not yet established itself widely,” she stated.

Scientists are particularly worried about the virus’s potential to trigger a larger outbreak in Australian wildlife. Dale Wright, acting director of conservation science at BirdLife Australia, warned that the arrival of sick birds on land could lead to new infections. “If a bird comes ashore and dies, it might attract scavengers like gulls, which could then act as vectors for the virus,” he explained. This scenario could pose a significant risk to the continent’s ecosystems, especially since many seabird species are already vulnerable to disease.

The recent cases in WA also raise concerns about the broader impact on the region’s biodiversity. Last week, Australian scientists revealed that over 13,000 seal pups had died from the H5N1 strain between October of the previous year and January. Penguins and petrels were also among the casualties, underscoring the virus’s ability to affect a wide range of marine life. With over 60 reports of sick or dead birds submitted to a nationwide hotline over the weekend, the situation is growing more urgent.

“The virus has spread around the world, and seabirds are already highly threatened. This is bad news for them too,” said Simon Gorta, an ecologist at the University of New South Wales. He added that while skuas are often implicated in disease transmission, it is not their fault. “They are simply doing what they naturally do—scavenging for food, which can inadvertently spread the virus.”

Experts are now debating the likely path of the H5N1 strain’s spread within Australia. While the disease originated in the northern hemisphere and caused widespread devastation there, the first signs of its arrival in the south have led to speculation about its future trajectory. Dr Roman noted that the northern coastline might be the first to experience a wave of infections, given the migratory routes of many seabirds. However, she acknowledged that an Antarctic origin remained a possibility. “The virus could have arrived via birds that travel between the southern and northern hemispheres, or through human activity,” she said.

As the virus continues to spread, biosecurity measures are being reinforced to prevent further outbreaks. Researchers are urging the public to report any sightings of sick or dead birds or marine mammals, while advising against direct contact with the animals. “If you find an affected bird, avoid handling it and instead take photos or videos to document the case,” said a spokesperson for the Emergency Animal Disease Hotline, which is now receiving a surge in reports. The hotline’s number, 1800 675 888, has become a critical tool for tracking the virus’s movement across the region.

With the confirmed cases in WA, scientists and policymakers are closely monitoring the situation to determine whether this marks the beginning of a larger epidemic. The virus’s presence in Australia could have far-reaching consequences, threatening both wildlife and industries that rely on healthy bird populations. As the first wave of infections takes hold, the focus remains on containment and understanding how the H5N1 strain will adapt to new environments in the southern hemisphere.