Bird flu has claimed its first Australian sea lion and dolphin. How does the virus get into these animals?

by bpckle | Sep 16, 2026 | In the Media

A rare Australian sea lion (Neophoca cinerea) on Kangaroo Island has been confirmed to have died from highly pathogenic H5N1 bird flu. The sea lion had recently been attacked by a shark, weakening it. Testing revealed the cause of death was the virus. Another dead sea lion is being investigated.

The first confirmed H5N1 death recorded for this species in Australia marks a significant and worrying moment for Australian wildlife. These sea lions are the rarest pinniped to breed on our coasts. They’re considered endangered, as their population is under 12,000. This species of sea lion breeds slowly, meaning even a limited outbreak of bird flu could be very bad news for breeding colonies.

The strain of bird flu now circulating in Australia and New Zealand has evolved to infect some mammal species as well as birds. Since 2021, it has decimated some seals and sea lion species overseas, especially in South America.

The virus is even capable of infecting and killing dolphins.

But how does the virus pass between these animals? How do seals and dolphins actually get the infection?

There’s much we don’t know. But here’s what we do.

Bird (and mammal) flu?

The highly pathogenic H5N1 strain of bird flu (avian influenza) was first detected in 1996. Highly pathogenic means it is capable of causing severe disease.

In 2020, the virus mutated into a new, more deadly variant capable of infecting more species. It is no longer just a threat to birds.

Since 2021, this strain has caused mass die-offs in pinnipeds (seals, sea lions, walruses and so on). In Argentina, more than 17,000 southern elephant seal pups died. After the virus reached Australia’s Heard Island, drone surveys identified more than 13,000 dead pups from the same species.

Some pinnipeds were able to catch older bird flu strains. But these mainly affected their respiratory tracts. The newer highly pathogenic H5N1 strain can also invade the brain and nervous system of mammals.

Sea lions have been found with encephalitis, brain inflammation and other neurological signs before death.

In Florida, a bottlenose dolphin infected with H5N1 was found to have the highest concentration of virus in its brain.

How do pinnipeds catch the virus?

The way the virus gets into pinnipeds is likely from birds. When sick seabirds infected with the virus die on the islands used by sea lions for breeding, the virus can jump across to the mammal. This can be through direct contact, scavenging carcasses or exposure to contaminated sand, rocks, water, faeces or mucus. Sick birds can and do sneeze and cough, spreading viral particles.

Direct transmission from mammal to mammal is suspected, though not yet conclusively proven in most wild marine mammal die-off events.

But the fact so many elephant seal pups died rapidly suggests the virus is able to spread between them. Transmission between elephant seals is suspected to have occurred in Argentina. It’s highly likely that the virus can spread faster in dense seal and sea lion colonies.

Pinnipeds, too, can sneeze and cough, which would help spread the virus. One researcher testing transmission reportedly had a seal sneeze in their face. They then contracted severe conjunctivitis in the eye. The bird flu virus was detected.

But what about whales and dolphins?

So far, so logical. But how can dolphins and other cetaceans contract the virus?

After a dolphin washed up dead near Goolwa, South Australia, it tested positive for H5N1 – the first case in Australia.

How did it happen? SA chief veterinary officer Dr Skye Fruean told the ABC it was likely the dolphin had “eaten a bird or interacted closely with a wild bird”.

This is possible, but we don’t know for sure. What we do know is that this H5N1 strain has been found in a range of dolphin species around the world.

So far, there’s little evidence of large whales being infected with bird flu. A juvenile dead whale washed ashore at Victor Harbour was found not to have the virus.

How long can the virus survive in the environment?

Viruses can survive outside a host, though typically not for long.

The H5N1 influenza virus generally survives longest in cool, moist conditions. It can remain infectious for days and sometimes weeks in water, depending on temperature, salinity and sunlight.

In hot, dry environments, survival is much shorter.

Carcasses can act as temporary reservoirs of the virus while tissues remain fresh.

This is one reason why beaches and breeding colonies can be transmission hotspots during an outbreak.

What can we do?

There’s no real way to stop the spread of H5N1 now that it’s here. But there are many ways we can reduce its impact.

Removing carcasses safely is crucial, as it removes these viral reservoirs and stops it getting into Australia’s many scavenging animals.

Investing in better monitoring and detection is essential if we are to slow the spread by helping us to target affected populations.

We must ramp up protection for endangered species, reduce human pressures such as disturbance of seal colonies and plan to help depleted populations recover.

Ultimately, the death of this sea lion shows us that the burden of bird flu will reach far beyond birds. This strain of the virus is a wide-ranging threat able to affect entire ecosystems. We must do what we can to protect them.

Bill Bateman does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Our new research shows humans have maligned bandicoots for decades, making them more vulnerable to extinction

by bpckle | Sep 15, 2026 | In the Media

Have you ever found your lawn riddled with holes or heard a little sneeze from your backyard bushes?

Those are signs you might have a resident bandicoot. Bandicoots are nocturnal, rabbit-sized marsupials known for their pointy snouts, thin tails and large hind feet. Due to these features, they were originally misnamed after a type of rat from India, the pandi-kokku, or “pig-rat” (Bandicota sp.).

Bandicoots are native to Australia and New Guinea, but are recognised as a globally threatened group of animals.

Despite seeming small and innocuous, bandicoots have long been maligned by humans, particularly as digging mammals that rip up farms, parks and even suburban gardens.

Our new study suggests this fraught relationship has lasted over decades – but for reasons you may not expect.

A brief history of bandicoots

For millions of years, various species of bandicoot have roamed the Australian continent, from desert to coastline.

Tragically, since European colonisation, eight of the 15 existing bandicoot (Peramelidae) species have become threatened or gone extinct. The populations that remain have all declined in numbers due to pressures from invasive predators, such as cats and foxes, as well as habitat destruction.

However, humans have also directly contributed to their decline.

Our latest research takes a closer look at how humans and bandicoots have interacted throughout recent history.

We did this by analysing more than 3,000 newspaper reports published in New South Wales between 1804 and 1954. These reports chronicle how people’s concerns about bandicoots evolved over time as an example of a human-wildlife conflict. These conflicts arise when the behaviour and needs of wildlife are at odds with those of people.

Our findings suggest there are three main reasons humans and bandicoots have had a troubled history.

1. A source of fascination – and food

In the early years of European colonisation, new arrivals enjoyed hunting Australia’s unusual animals. Bandicoots were trapped or shot for sport, food or fur. Hunters often sent their skins back to Europe for display, prompting some European artists to feature them in comical ways.

Bandicoots were also prized for their meat, with one newspaper article describing roast bandicoot as “one of the most deliciously delicate dishes going”. There were even reports of escaped convict prisoners surviving on bandicoot meat.

2. A pest to control

From the early 1800s, farmers and landholders grew increasingly frustrated with bandicoots because of their digging habits. In the bush, bandicoots forage using their long noses and claws to dig up grubs, roots and mushrooms buried in the soil.

But from the 1830s, bandicoots throughout regional NSW were reportedly digging up maize and potatoes. People were soon using the term “bandicooting” to describe theft of any garden produce.

Farmers and landholders used various strategies to keep bandicoots out, including putting up fences, training patrol dogs and even coating crop seeds in tar and ashes.

But the most popular strategy was lethal control. Poisons, traps and guns were used to legally kill many native species under the Pastures and Stock Protection Act (NSW). From the 1880s until 1930, people could present the scalps of caught animals in exchange for cash. The Bathurst protection board received nearly 19,000 bandicoot scalps in 1906 alone.

3. A vehicle for disease

By the 1920s, the war on bandicoots shifted to the suburbs where residents grew increasingly worried about ticks, small parasites which feed off the blood of their hosts.

Early research into the most common species in eastern Australia, the paralysis tick (Ixodes holocyclus), did not single out bandicoots as a key host. But that all changed in 1924, when veterinary researcher Ian Clunies Ross collected ticks from bandicoots and concluded long-nosed bandicoots (Perameles nasuta) were their favourite host.

We now know bandicoots are just one of many animal species that host paralysis ticks, such as rats and possums. But once Ross’ claim was widely published in Sydney newspapers, the damage was done to the bandicoot’s reputation.

When a deadly new disease was discovered in the 1930s, bandicoots quickly became the prime suspect. Q fever was first found in workers at a Brisbane abattoir. After an infected worker thought he saw a bandicoot walking into a cowshed at night, bandicoots were suddenly to blame. Today, it is well-known that farm animals are the main spreaders of Q fever.

From conflict to co-existence

Many Australians still have a complex relationship with bandicoots, regarding them as pests to avoid or even eliminate.

This highlights the long-held misunderstanding we have about bandicoots. Bandicoots actually play a vital role in Australian ecosystems by digging up vast amounts of soil, spreading beneficial fungi and reducing the risk of bushfires.

So how can we better support our bandicoots?

For starters, we can fund more research into their behaviour, diet and role in the environment. Studying their nutritional needs may help us understand why they venture onto farms and into backyards.

We must also protect their habitat. Bandicoots are ground-dwelling mammals who like to nest in shrubs and grasses in the daytime. Conserving even small pockets of bushland can provide much-needed habitat.

When they venture out after dark, bandicoots are vulnerable to being hit by cars or killed by invasive predators like cats and foxes. If you have a pet, keeping them indoors at night is one way to keep bandicoots safe.

Most importantly, we need to set the record straight about bandicoots. Through education, we can correct misconceptions and teach Australians about the critical role bandicoots play in nature. After misunderstanding them for decades, it’s time we learn to love these little diggers.

Annabel Ellis has received funding from the Paddy Pallin Foundation and the Royal Zoological Society of New South Wales, as well as the Holsworth Wildlife Research Endowment from the Ecological Society of Australia.

Dieter Hochuli receives or has received funding from the Australian Research Council, City of Sydney and Inner West Council. He is president of the Ecological Society of Australia.

Peter Banks receives funding from the Grains Research and Development Council, Australian Research Council, Australian Forests and Wood Industries, New South Wales Environmental Trust and Pacific Conservation Foundation.