We don’t know how well threatened species fight off bird flu – but we need to

Source: The Conversation (Au and NZ)

Lethal bird flu is now spreading in Australia. This is bad news for many native species.

New federal government analysis suggests close to one in five Australian bird and mammal species is at high, very high or extreme risk. But this risk assessment omits something vital – how genetically well-equipped the species is to fight the virus.

While species such as black swans are likely to be very hard-hit, others such as wild ducks are expected to be less affected. One reason for this is different immune systems – some are more or less able to fight the virus. But there’s a more significant factor – how much variation there is in key immune system genes across populations.

Right now, we don’t have an overview of which threatened species are at highest risk based on this. If we urgently create a national immune-risk map for species at risk, we can act to protect those in most danger.

Why immune gene variations matter

When a virus enters an animal’s body, its immune system must first detect it, then respond. Key immune genes help determine if an animal fights off infection, becomes seriously ill or dies.

Different individuals will have slightly different immune responses based on variations at different immune genes. Some variants will allow an individual to survive the virus, and others won’t. This is why diversity in these genes is critical across the species.

Large wildlife populations often have a wide array of variants at each immune gene. This acts as biological insurance – when a new disease arrives, some individuals will be more able to survive. But if a species becomes threatened and its population falls, it’s likely to lose much of this protective diversity.

If the remaining individuals share similar vulnerabilities, a lethal disease such as H5N1 bird flu could be enough to push the species closer to extinction.

Threatened species are often immunologically fragile

Australia’s wildlife faces threats such as habitat loss, climate change, invasive species, pollution and disease. These threats not only reduce population size – they erode genetic diversity.

Small, fragmented populations may have enough genetic diversity to look viable in the short term. But when a new disease arrives, they may lack the breadth of variation at the immune genes needed to survive the new disease. This is a large, hidden vulnerability.

The orange-bellied parrot is a species that worries us deeply. The small, migratory parrot is one of Australia’s most endangered birds. Just 86 birds are left in the wild, with a few hundred more in captive breeding populations.

Our previous research found the parrot has suffered a dramatic loss of genome-wide diversity over the past century – including variation in immune genes.

If H5N1 infects these parrots, they may lack the immune gene variants needed to buffer the species against severe disease.

Tasmanian devils are similarly at risk. These iconic marsupials have critically low immune gene diversity due to population bottlenecks over the past 5,000 years. This left them vulnerable to the contagious devil facial tumour disease, which saw populations plummet with local declines of 95%, and an estimated 80% decline across Tasmania since the disease arose in the 1990s. Our preprint research shows facial tumour disease is still eroding immune gene diversity.

These scavengers are likely to be exposed to bird flu by eating carcasses, and we know which devil populations eat seabirds. The question will be whether devils have enough immune variation to respond to H5N1.

How a national immune-risk map could help

While we know how some species are likely to respond to the virus, the picture is far from complete.

We could fill in the blanks quickly, using DNA samples held in museums or from animals in zoos to generate genomic data on many more species.

We could then analyse immune gene variation across different populations of each species to measure how diverse they are. This approach could reveal populations that have lost important immune variants and may be particularly vulnerable to bird flu.

The Threatened Species Initiative, has collected this data for more than 125 threatened species. But there are hundreds more threatened animal species for which we have no data and no samples.

If we worked quickly to create a national immune-risk map, wildlife managers could focus surveillance, vaccination and protection efforts on the populations likely to be at most risk.

Importantly, they could establish new captive populations before the virus arrives, using breeding programs to maximise immune fitness and keep inbreeding to a minimum.

This is not science fiction. We led immune-guided conservation work in Tasmanian devils, where data on immune genes shape decisions around breeding. The end result: devil joeys with stronger immune systems.

If we use this approach for more at-risk species, we could better protect wildlife from bird flu and future diseases.

No time to waste

Responses to wildlife diseases are often reactive. Animals start dying in large numbers and then we investigate. This approach will be much too slow to respond to the fast-moving H5N1 strain.

Australia has world-leading wildlife genomics expertise, valuable museum and zoo collections, threatened species recovery programs and growing genome resources.

What’s missing is a coordinated way to translate immune gene data into practical action.

It’s not too late. But we have to act fast to identify species and populations with low immune diversity and roll out measures before irreversible losses occur.

Katherine Belov receives funding from the Australian Research Council, including through the ARC Centre for Excellence in Peptide and Protein Science.

Carolyn Hogg receives funding from the Australian Research Council including through the ARC Centre of Excellence for Advanced Peptide & Protein Engineering, the NSW government and the Australian Government. She is affiliated with the Biodiversity Council.

Original source: https://analysis1.mil-osi.com/2026/08/05/we-dont-know-how-well-threatened-species-fight-off-bird-flu-but-we-need-to/