New Zealanders are being encouraged to prepare for the likely arrival of bird flu.
The strain of H5N1 bird flu affecting birds and mammals around the world hasn’t reached Aotearoa and its Pacific neighbours yet. However, it spreads easily between wild birds, and the government is urging New Zealanders to take steps now and learn how to recognise possible signs of the virus in birds.
The Science Media Centre asked experts to comment on how the virus could affect our wildlife.
Professor Philip Seddon, Department of Zoology, University of Otago, comments:
“While the most virulent strain of bird flu has not yet been detected in Australia, it has established in many other countries globally, spread by the movements of wild migratory birds. That will be the pathway avian bird flu might, or some say will, find its way to Aotearoa – wild birds, not human imports. Species that flock or breed in large groups and which can come into contact with migrants from overseas are most at immediate risk, such as gulls and godwits. Well-spaced and solitary breeding species, such as hoiho (yellow-eyed penguin) or tawaki (Fiordland penguin), are less at risk.
“Its high pathogenicity means large-scale deaths of wild birds is possible, and there could even be spill over into mammals, including humans.
“Currently it’s a wait and see game – but not really as passive as that sounds, it’s more about monitoring and surveillance to detect the first arrival as quickly as possible and then to move to protect commercial birds as a priority.
“Not to say that wild birds are being forgotten – not at all – DOC is a key part of the surveillance and response planning and is even involved in trials of a vaccine using captive native birds such as kaki (black stilt). Because it will likely require two doses to be effective, any vaccine won’t be an option for wild populations, but could protect key captive population of native bird species.
When it arrives, there will likely be no ability to eradicate, so it’s going to come down to management in order to minimise impacts…. and a bit of luck.”
No conflicts of interest.
James Russell, Professor of Conservation Biology, University of Auckland, comments:
“Highly pathogenic H5-N1 (HPAI) avian bird flu is a very transmissible new virus that has high death rates and can jump from animals to humans. It poses as severe a risk to birds as SARS‑CoV‑2 (COVID) did to humans. Islands are particularly vulnerable as the arrival of novel species and diseases is known to disproportionately impact their biodiversity and people. However, this isolation that fosters the vulnerability of islands also affords them some protection. They can be the last places in the world to be impacted, and this allows them to prepare for what is coming.
“We will know quickly when bird flu arrives because the mortality is substantial. Waterfowl and seabirds are known to be highly impacted, because they gather together, and this also means they will be observed dying in large groups.
“New Zealanders have a strong engagement with the natural world and so most likely a member of the public will be the first to observe bird flu arriving on the main islands of New Zealand. As we saw for COVID19, once it is established, it will spread rapidly across the country. Only once it arrives in New Zealand will we actually know which of our species are impacted, and to what extent.
“Vaccination provides resistance and our most vulnerable bird populations can be vaccinated, where we can invest in this. As we also know from COVID19, waves of infection will occur, and this will continue for some years, but over time these will dampen.
“Our strongest lessons come from the locations which were first impacted and now have the longest history of observations of mortality, virus behaviour, and recovery. These locations were unprepared, underprepared or could not realistically prepare. From these we have learnt the worst-case scenario, as we also did for COVID19. Like us, our neighbours in Australia will have had the opportunity to prepare. From these locations we will learn the best-case scenario of how and which types of preparations most reduce impact.
“The threat of HPAI for our valued avian biodiversity is high, but we can take hope that we can prepare and learn from others. We also have the tools and commitment (such as the Predator Free New Zealand initiative) to manage other threats to birds and build resilience in their populations to the challenges they face in the 21st century.”
Conflict of interest statement: Professor Russell has supported DOC in avian-flu readiness preparation, and in the past was the chair of the board of BirdCare Aotearoa.
Professor Brett Gartrell, Group Leader, Wildbase, School of Veterinary Science, Massey University, comments:
“In the last three years (2021-2024) there has been an unprecedented mortality of wild birds throughout the world due to the avian influenza virus with only New Zealand and Australia remaining free of the highly pathogenic subtype of the virus (clade 2.3.4.4b HPAI A(H5N1). During this period, over hundreds of thousands of dead birds have been recorded from over 2600 separate mortality clusters in wild bird populations, however, the actual number of birds affected is estimated to be much higher. Deaths due to this strain of the virus have been reported from almost every country in Asia, Europe, North and South America and Africa. Most recently the virus has caused
deaths of seabirds in Antarctica. Many bird species are affected, including seabirds, shorebirds and birds of prey. The virus has occasionally spilled over into mammals and has caused isolated deaths in carnivores such as cats, dogs, bears, foxes and skunks. Sustained mammal to mammal transmission has occurred three times now, once in farmed mink, once in dairy cows in the USA, and an ongoing mortality in elephant seals in South America and associated subantarctic islands. The number of human infections with this strain of the virus is fortunately very low but the mortality rate in people that are infected is high.
“Avian influenza viruses are a complex group of viruses that are of importance to bird and human health. Viruses evolve rapidly and this current strain of avian influenza is particularly concerning because it has high transmissibility, can infect hosts across species barriers, and is much more likely to cause severe disease and death in some wild bird species.
“If the H5N1 strain enters Aotearoa New Zealand, the consequences for wild bird populations and poultry flocks may be severe. The Ministry for Primary Industries (MPI) has primary responsibility for exotic disease surveillance, investigation of unusual mortality clusters and the control of exotic disease incursions in animals and plants in Aotearoa New Zealand. MPI has a targeted surveillance programme where wild birds, particularly ducks, are screened for avian influenza viruses. Bird mortality events are also routinely reported and investigated by MPI’s incursion investigators.
“Our geographic isolation and strict biosecurity laws are barriers to this disease entering Aotearoa New Zealand. Although our biosecurity laws currently prevent the importation of live birds, smuggling is a potential route for entry of the virus. Migratory shorebirds and seabirds are also possible vectors of the virus into the country. If the disease enters the country, it may move around the country in wild birds and traded poultry unless it is quickly eradicated.
“In a recent outbreak of a pathogenic avian influenza H7N7 strain in Australia, control and eradication were achieved by culling over 433,000 birds, including poultry, turkey, farmed emus, and pet birds. If H5N1 were to occur in a poultry shed without being detected in wild birds, MPI would likely adopt a similar eradication strategy to prevent the virus from becoming established in New Zealand. However, if the virus is detected in wild birds in New Zealand, eradication would likely not be attempted.
“More details of the New Zealand response to an incursion of HPAI are becoming available. Once the virus becomes established in wild birds, MPI will pass responsibility for operational responses to the Department of Conservation on conservation land, and local and regional councils elsewhere. We are waiting on detailed guidelines of what responses will be allowed, but overseas, intervention has been limited to closing affected areas to the public, and collection of bodies and/or euthanasia of sick birds by people wearing appropriate protective gear. The disposal of infected birds is also a difficult problem as the virus remains active in dead birds for same days, putting predators and scavengers at risk.
“The Department of Conservation is working on vaccination as a protective measure for some of our most endangered species, but any incursion of the virus into New Zealand is likely to have far-reaching effects on domestic and wild birds and the people who work with them. It’s very difficult to predict how fast the virus would move through the country because it has different effects in different species of bird (or mammal). For example, the spread in Antarctica has been much slower than feared, probably because Antarctic penguin species have not been severely affected, however gulls, albatross and skua have. Waterfowl and seabirds are generally thought to be susceptible to the virus and these birds are the most likely way the virus will spread within New Zealand.”
No conflicts of interest.
Professor Dianne Brunton, School of Biological Sciences, University of Auckland, comments:
“This week the Biosecurity Minister Andrew Hoggard released a statement encouraging kiwis to think about what they would do should avian influenza (HP5N1) arrive in Aotearoa/New Zealand – there is little doubt it will arrive and once it does, it will have an impact on the poultry industry, those of us that keep backyard chickens, the bird pet industry, and our wild bird populations. There is also the potential of spillover into dairy cows, something that is rare but is happening in North America.
“MPI rightly point out that eradicating HP5N* (HPN1 and its variants) will not be possible, and one of the reasons is the mixing of wild and domestic populations on a large scale. Overseas experience shows that HP5N* moves quickly through domestic and wild populations. Birds can have multiple infections of different variants, and this further increases the risk of more variants arising – as we all know from the COVID experience.
“I am a conservation biologist with a particular interest in conservation of threatened bird species. We know that HP5N* is an enormous threat on the horizon for our wild bird populations. Aotearoa New Zealand wildlife already faces the significant challenges of introduced mammalian predators and pests, and habitat loss and degradation. Globally, there has been a recent escalation in the number of new species being detected with the highly pathogenic virus HP5N*. It is now common across most families of birds from raptors to sparrows – in the past it was most common in ducks and geese.
“MPI, the Department of Conservation, and a good number of NZ scientists, have been concerned and preparing for its arrival over the last couple of years. This preparation includes assessing risks, field monitoring, and testing vaccines in captive birds (although the vaccine does provide 100% immunity and requires 2 doses). Obviously trying to vaccinate wild populations of birds is not feasible except in rare cases such as kakapo.
“So which birds are likely to be impacted the most and how will it get here? Recently, HP5N* has been found in Antarctica and the Falkland Islands and it is likely circulating among seabirds in the region. Aotearoa New Zealand is considered the seabird capital of the world; we have more seabird species in our waters and across our islands than anywhere else in the world. Hence, the most likely route into New Zealand is through the movement of seabirds, although it could also arrive from migratory shorebirds from the north. Most seabirds are colonial breeders which means you get large concentrations of animals on small islands. Diseases move quickly through concentrations of animals. Many of our land based threatened and endangered bird species are on offshore islands; logical as these islands are where we can control introduced predators and pests. You can understand the concerns of conservation biologists.
“In my view, there are three significant risk factors to our wild birds that help us understand the likely impacts of HP5N* and plan:
- Low population size and low genetic diversity. Small populations tend to have low genetic diversity, and hence typically low resilience against threats such as disease and environmental challenges.
- Location. Many of our threatened and endangered species are on protected offshore islands – an excellent strategy against introduction mammalian predators but these islands are also home to highly mobile species such as seabirds and species such as kaka that move long distances. The species most at risk are obviously those only found in a few locations – all your eggs in one basket is a risk from any threat. But DOC has been proactive in this space and translocations have been ongoing for decades to minimise this general risk.
- Behaviour of the birds. Birds that exhibit social behaviour or aggregate are at high risk of transmission of the virus. For example, colonial breeding seabirds, birds that flock or roost together at certain times of the year, such as korimako/bellbird, tui, and shorebirds. Migratory or dispersal behaviour also increases the risk of spread. We have cuckoos that migrate north from New Zealand to the South Pacific islands each winter, returning in the spring to breed. If/when the virus gets to NZ then it could go from here to the Pacific Islands. Some shorebirds migrate to the northern hemisphere through Asia and others migrate from the South Island to the North Island. Most of our seabird species forage and move long distances, many have long distance patterns of movement throughout the Southern Ocean and then breed in concentrated island colonies.
“A prime example of high risk of HP5N* impact is to our endangered Tara iti/the New Zealand Fairy Tern; fewer than 40 birds remain. Tara iti are only found in Auckland/Northland where there are currently just 10 breeding pairs nesting mostly on the east coast in summer and roosting together with other seabird/shorebird species around the Kaipara Harbour in winter. HP5N* has spread to many tern species in other parts of the world so our Tara iti are unlikely to have natural resistance – especially as their genetic diversity is low. There are many other examples, but this one is of particular concern for we have recently ramped up efforts to protect this species.”
No conflicts of interest.