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

Brown skuas. giant petrels are a common sight offshore in southern Australian waters in the winter months, but they will rarely risk venturing on to land.

So when two of these birds were discovered sick – on beaches a few kilometres apart on Western Australia’s southern coastline – it was a sign something might be wrong.

On Monday it was confirmed the giant petrel had tested positive for the H5N1 strain of avian influenza. two days after the case was confirmed in the skua. Both birds have since died.

The virus has killed millions of birds. mammals around the world since 2021 but, until now, Australia was the only continent it had failed to reach.

Now governments. wildlife experts are waiting anxiously to see if the two cases represent the beginning of a wave of infections, fearing devastating consequences for Australian wildlife and industry.

Almost 60 reports of sick and dead birds in Western Australia were made to a nationwide hotline at the weekend.

Australia’s chief veterinary officer. Dr Beth Cookson, said there was no sign that the two infections had spread to other birds. But the cases have put experts and government agencies on high alert.

Because the disease first emerged in the northern hemisphere. much of its devastation has occurred there, experts told the Guardian it was thought more likely that, if it reached Australia, it would affect the northern coastline first.

But an arrival from Antarctica and its surrounds had always been seen as a possibility.

“Biosecurity had our eyes on the northern hemisphere,” said Dr Lauren Roman, a seabird researcher at the University of Tasmania’s Institute for Marine. Antarctic Studies.

“We had been warned about the arrival of migratory shorebirds. seabirds and that the virus could come in with them.”

She said for more than two years there had been ongoing surveillance by agencies. scientists all around Australia, constantly checking for the disease. But, until now, all tests had returned negative.

Giant petrels. brown skuas both breed in Antarctica’s summer but leave the frozen continent when temperatures tumble, spending the winter months foraging at sea to the north, including in Australia’s southern waters.

Both the birds will also scavenge for food. Roman said this practice is thought to be one way the disease could have spread around Antarctica. how these two birds may have contracted the disease.

“Skuas have been implicated in the spread [of the disease] but it’s not inherently their fault,” said Simon Gorta, a researcher. ecologist in the Centre for Ecosystem Science at the University of New South Wales.

“It’s a virus that has spread around the world. seabirds are already highly threatened so this is bad news for them too.”

More than 13,000 seal pups died from the disease between October last year. January, alongside penguins and petrels, Australian scientists revealed last week.

“There’s potential that there could be other birds coming up – other species. other individuals – that could come in to our shores because they are sick,” said Dale Wright, the acting director of conservation science at BirdLife Australia.

These are pelagic bird species – meaning they sleep. forage at sea – and they rarely come ashore unless they are either sick or they see something inviting on a beach, such as a whale carcass, to feed on.

But Roman. Wright both said if a sick bird came ashore and died, it could easily be fed on by other birds – including gulls – which could then move the disease into other populations, making it impossible to eradicate.

Anyone who finds sick or dead birds or marine mammals is advised to avoid the animals. not handle them, and instead take photos or a video and call the Emergency Animal Disease Hotline on 1800 675 888.