Now bird flu has hit seagulls a 'super-spreader' event is more likely

analysis H5N1 detected in humble seagull threatens to spread bird flu beyond the beach Mon 3 Aug 2026 at 3:53pm It's hard not to think of Australia's hotel quarantine system during the COVID-19 pandemic while waiting to see what would happen with the animal equivalent, a global bird flu panzootic, on our shores. In the early stages of the COVID response we were given the daily numbers of returning Australians testing positive to the virus. All the while we held our breath waiting to see if it would spread out into the wider community. It's been a similar feeling as migratory birds from Antarctic waters started washing up in mid-June with the H5N1 avian influenza that has swept the globe killing millions of animals. Infected giant petrels and a brown skua, that travel seasonally to chill in the ocean off Australia in winter, were kept in vet clinics as we kept our fingers crossed there would be no local spread. But now the humble seagull getting H5N1, coupled with a mass mortality of greater crested terns, marks a new stage for bird flu's spread in Australia. Until the first seagull was detected with H5 in South Australia last week, the only birds with the virus were terns and those migratory seabirds which stick to the ocean or beaches. But seagulls, the common name for the silver gull species, can move vast distances around the country taking advantage of resources be it nicking chips or hanging out at tips. Potential for long-distance spread Seagulls can be found nearly everywhere in Australia, from beaches to cities, freshwater systems, mountains and landfills. They even pop up in the middle of the country when big rains fill up sites like Kati Thanda-Lake Eyre. This lifestyle gives them the potential to act as a crossover species in spreading the virus to a range of different environments and other bird species. "They're more cosmopolitan in their requirements, [eating at] tips, shopping alleys," Chris Purnell, the wetland and migratory shorebirds manager at Birdlife Australia, told me. "They'll mingle with everything and often parasitise [steal from] other birds and eat their eggs." Seagulls also poo in a lot of places, which is one of the big ways the virus spreads. They spend a lot of time around greater crested terns, which have tested positive to H5N1 in SA and Victoria so far, mixing together in large groups. Both species are coming into their nesting seasons where they can form colonies of thousands. Silver gulls in South Australia nest between June and December with the exact timing varying colony to colony. To borrow a term from the COVID-19 pandemic, those are potential super-spreader events. And they are a real concern when this particular type of H5N1, the clade 2.3.4.4b, wiped out millions of wild and domestic birds and thousands of seals around the world in just a few years, including gulls. The black-headed gull, a close relative of the silver gull, has been the subject of mass die-offs in Europe from this type of H5N1, with an estimated 51,000 adult birds dying in 2023 in Poland. Mass bird deaths are a live concern given what has happened elsewhere in the world and with the first Australian mass mortality of 49 dead greater crested terns over the weekend in SA. Australian Chief Veterinary Officer Beth Cookson said on Monday it had taken a little longer than expected to see a localised spread occurring since the first migratory bird detections. "Now that we have got that localised spread, this is following a fairly predictable curve in terms of the number of infections," she said. "Particularly during a period of year as we might start to see birds start to congregate more. "We know when birds and other animals congregate that's where we get more risk of circulation of the virus and onward spread." H5N1 here to stay Technical advice last week to the federal government puts Australia past the point where the virus may have been eradicated, particularly with a local spread occurring in SA. Skye Fruean, the chief veterinary officer of South Australia, said the disease was here to stay. "Once we started to get that really strong evidence of that transmission between the crested terns, that does change things in terms of our decision making." LoadingDr Fruean told SA Country Hour on Friday that surveillance was still the primary focus but state and federal governments were looking now at what else they should be doing in terms of virus management. That includes discussions around what should trigger a mandatory housing order for free-range chicken operations. "At this point in time it is an option open to jurisdictions," Dr Fruean said. Bringing chickens indoors keeps them away from the potential exposure to water contaminated by wild infected birds and the latter's faeces. That's because chickens are highly susceptible to this strain and more than 100 million have died or been culled in the US since its first outbreak in 2022. But it's still early days yet, with states weighing up the risks and whether chickens need to be locked down. Duck, duck, virus The biggest turning point for different states could be when the virus shows up in water fowl like wild ducks. Ducks are thought to have co-evolved with bird flu viruses like H5 as they can be silent spreaders showing little signs of illness. The virus also spreads rapidly among ducks as it can survive for multiple days within freshwater bodies that ducks both defecate in and eat from. It's not out of the realms of possibility that a bird such as a seagull or a pelican could now be the bridging species that takes the virus from the coast and brings it to ducks. When I rang Dr Purnell on Friday he was visiting Victoria's volcanic lake system, west of Melbourne, where seagulls were starting to gather for nesting. Ducks and other freshwater birds are also highly mobile and move between major water systems. So, the virus has the potential to move big distances and make its way around the country from a single incursion. Past tracking studies of species like ibis and spoonbill, for instance, on the east coast of Australia show a 2,000 kilometre flyway over the Murray Darling Basin. Individual birds were tracked flying all along the system and up to northern Queensland. With the local spread of the virus in SA, there are major areas of concern for initial outbreaks in internationally significant wetlands like the Coorong at the mouth of the Murray River. The Coorong is home to more than 200 bird species, and is a major stopover for millions of migratory shorebirds which start arriving in September from the northern hemisphere each year. They too will be vulnerable to the virus. While we can't predict what exactly will happen from now with the virus's spread, any wishful thinking it wouldn't establish in local birds is past. And as federal agriculture minister Julie Collins said on Monday, we should expect to see an increase in the number of birds getting H5N1 in Australia. "Sadly, we do know that once the H5 bird flu is spreading in wildlife and the natural environment, it is not possible to avoid significant losses, which is what we are starting to see now," she said. "Australians should expect to see more [H5] spread and larger numbers now of wildlife being affected." Anyone who sees a dead or sick bird is asked not to touch it and report it to the Emergency Animal Disease Hotline on 1800 675 888.