New Zealand has so far avoided the strain of avian influenza causing mass mortalities of wild birds and mammals around the world. But geographic isolation was not enough protection for one biodiversity hotspot.
The subantarctic island of South Georgia in the South Atlantic Ocean is about as remote as you can get. About 2000km east of the southern tip of South America, 1500km from Antarctica and 1400km from its nearest neighbour, the Falkland Islands, it is an exposed part of a submerged mountain chain linking South America to the Antarctic.
The long, narrow, crescent-shaped island is dominated by jagged ice-capped peaks rising steeply from the sea. More than 160 glaciers punctuate its mountain spine, some calving directly into the ocean. Snow and ice blanket more than half of the island all year round and powerful polar winds bring freezing rain and snow even in summer.
Despite its barren, rugged terrain and inhospitable climate, every Southern Hemisphere summer the largest concentration of sea mammals and seabirds in the world gather there to breed. They come for its year-round ice-free shores and the bounty of food in its waters. South Georgia lies within the Antarctic convergence zone – a marine belt where warm waters from the north meet cold polar seas, creating a nutrient-rich marine environment full of krill, fish and squid.
South Georgia is often described as the “Serengeti of the Southern Ocean” or the “Galapagos of the Antarctic”. Before the recent avian influenza outbreak, this British Overseas Territory was home to more than 65 million pairs of breeding birds, five million seals, 400,000 southern elephant seals and seven million penguins.
Naturalist and broadcasting legend Sir David Attenborough has filmed on South Georgia many times – showing iconic locations such as St Andrews Bay, where 150,000 pairs of king penguins jostle for space and a trek to the sea risks a bark or a nip from the “beach master” (the dominant bull) protecting his harem of up to 100 female elephant seals.
In the 2020 film South Georgia: A Visitor’s Guide, Attenborough described South Georgia as “a global rarity”, one of the very few recovering ecosystems in the world. More than two centuries of damage caused by human activities such as sealing and industrial whaling have been reversed by habitat restoration projects, strict biosecurity measures, and the eradication of invasive plants, rodents and European reindeer introduced by hungry and probably homesick Norwegian whalers. The film was produced by the government of South Georgia and the South Sandwich Islands and is required viewing for visitors.
The summer season is the busiest time of year at South Georgia , when numbers of personnel will peak at about 40, comprising scientists, biosecurity officers and maintenance teams.
Widespread deaths
Since the H5N1 strain of the avian influenza virus (HPAI) first appeared in wild birds in South America in late 2022, British Antarctic Survey scientists on South Georgia have been watching for signs. In the spring of 2023, at their research station on Bird Island off the northwest tip of South Georgia, the scientists noticed all was not well. In September, a young southern giant petrel was observed unable to walk or fly, its head and wings were drooping.
The bird died the next day and was scavenged by brown skuas and other giant petrels. In October, brown skuas and kelp gulls on the main island tested positive for HPAI at two different locations, the first confirmed cases in the Antarctic region.
In December, southern elephant seals and Antarctic fur seals were observed having difficulty breathing, taking short intakes of breath, coughing and with viscous fluid around the nasal passage – all symptoms of HPAI in mammals. Sequencing indicated the infection was likely to have been introduced through migratory birds from South America.
Attenborough described South Georgia as “a global rarity”, one of the very few recovering ecosystems in the world.
By the end of the 2023-24 summer season, 77 brown skuas, 38 gentoo penguins and 58 snowy albatrosses were suspected to have died from HPAI infection on Bird Island. It was also confirmed in five dead Antarctic fur seals but there were likely many more.
There were reports of dead albatrosses, king and gentoo penguins and a mass die-off of elephant seals on South Georgia, but government fisheries and environment director Mark Belchier says the number of deaths is unknown. “It appears that some beaches are likely to have been more [affected] than others, but we really don’t have a figure for the level of mortality that was observed last year.”
Tripping over carcasses
The recent boom in eco-tourism, sustainable travel practices and the demand to see unique wildlife in one of the world’s last remaining pristine environments has caused a huge spike in the island’s tourism industry. More than 100 expedition cruise ships and yachts visited South Georgia in the 2023-24 summer but there were fewer landings on shore.
One passenger quoted in The Guardian last March said the only place the ship could anchor was at Grytviken, the site of the former Norwegian whaling station and post office and museum, because there were so many seal carcasses on the beaches. Access to polar explorer Edward Shackleton’s grave in the cemetery nearby was prohibited “because there were so many dead seals blocking the way”, she said.
Marine biologist Eloise Berrier, who was a guide and zodiac driver on an expedition ship last summer, said she had people crying in her zodiac. “You are in a place to observe wildlife and then you see how fragile it is.”
In October, there were no signs avian influenza had returned when I visited as a passenger on the first Poseidon Expeditions cruise of the 2024-25 summer season to South Georgia.
“This year was different to last year,” says Poseidon expedition team leader Chris Bruttel. “We basically didn’t see any dead animals, but there were a lot fewer penguins and seals, not necessarily due to bird flu, as it was a very harsh winter in South Georgia – the coldest one since 1987 – which leads to a high mortality rate, especially among penguin chicks.”
But only one month later, scientists confirmed HPAI was back and in most locations around the island. Again, marine mammals were affected more than penguins and other seabirds.
This season, Antarctic fur seals, particularly pups, had the highest levels of mortality but it was a relatively low percentage of the overall number of pups, says Belchier.
Scientists, as well as government and UK Animal and Plant Health Agency officials, are continuing long-term monitoring to control the spread of the disease and looking for ways to mitigate its impact on wildlife, he says.
A team from New York’s Cornell University is also focusing on the spread of the virus and the development of immunity in a wide range of species.
“It has been suggested that some species may have been exposed to this or a similar virus in the past and may have developed some immunity from prior exposure,” says Belchier. “We should know more once this year’s samples have been analysed fully, including crucially, the level of immunity that may have developed in elephant seals.” He says scientists are still waiting for test results to show whether the bird flu strain is mutating and evolving.
Chicken farm scare
In the meantime, like South Georgia, New Zealand waits. The strain of HPAI detected on a commercial poultry farm at Hillgrove in Otago in December probably developed from interactions with local waterfowl and wild birds, but it was not the H5N1 strain circulating in wildlife around the world.
A strict biosecurity lockdown was ordered. About 200,000 birds were culled and the property was cleaned and decontaminated.
Mary van Andel, chief veterinary officer at the Ministry for Primary Industries, says extensive testing has shown no further sign of HPAI outside the Hillgrove farm. “We’ve carried out more than 5600 tests overall. This is a significant number of tests and gives us confidence that this virus has been contained to just the one property and that we are on track to stamp out this disease.”
Before the outbreak, New Zealand had never had a case of HPAI. Van Andel says our geographical isolation has protected us from HPAI in the past, but we can’t rely on it forever.
“Given the unpredictable journey of wild birds that can travel with HPAI, it may still arrive here. While we can’t prevent that, we can work together to reduce its impact.”
MPI is the lead agency if an HPAI outbreak occurs here, but it is working with Department of Conservation (DoC), the Ministry of Health, Te Whatu Ora and the poultry industry in a “one health” approach.
DoC director of terrestrial biodiversity Hilary Aikman says migratory shorebirds such as godwits, knots and sooty shearwaters are potential vectors for bird flu here. Shorebirds had finished migrating from the Northern Hemisphere by mid-October and sooty shearwaters returned to New Zealand by September. There’s no evidence to suggest they’ve brought H5N1 to New Zealand.
Seabirds such as giant petrels and polar skuas are potential vectors from Antarctica. These species migrate to our subantarctic and other islands when they disperse at the end of the Antarctic summer from April.
Aikman says if the H5N1 bird flu arrives and spreads in the wild bird population “we won’t be able to eradicate it from wild birds and management options will be limited”.
DoC’s focus will be on minimising the spread of HPAI on conservation land, not disturbing wildlife and supporting the health and resilience of threatened bird populations through conservation work such as breeding and predator control programmes.
It is developing plans to improve the detection of HPAI, reduce its spread and protect threatened species, including identifying high-risk sites and at-risk species, and has vaccinated five species of our most threatened birds living in captive environments, she says.
Forest & Bird group manager Duncan Toogood says DoC has been taking a proactive role in providing information to community and volunteer groups.
“Forest & Bird volunteers and staff work in a wide range of environments right across the country. We will proactively do whatever we can to support the avian flu response and help our species, but we know that there are limited options for action.”
NZ sea lion fears
That doesn’t give much comfort to the New Zealand Sea Lion Trust. Trustee and co-chair Bryony Alden says based on the mass mortality events in other flipper-footed species caused by HPAI, the trust is extremely worried about the potential impact the virus may have on pakake across their range. The current NZ sea lion population is about 10,000 individuals, making them the rarest sea lions in the world.
Alden says the stronghold of the breeding population is the Auckland and Campbell subantarctic island groups, which are extremely remote and expensive to reach, making data collection and responding to any crisis difficult.
University of Otago ecologist and penguin expert Thomas Mattern is more sanguine about DoC’s preparations if HPAI arrives in the subantarctic islands. “The quarantine procedures we have to go through to get to the subantarctic islands are the strictest I have experienced anywhere in the Southern Hemisphere – and I would argue highly effective at keeping invasive seeds and diseases out.”
In the past couple of years, DoC has added new procedures, particularly regarding potential H5N1 outbreaks. Whether that is enough in the eye of the public is a different question.
“I do believe more often than not the public is expecting DoC to perform miracles with ‘our tax money’, completely ignoring the fact that DoC funding gets slashed year by year with reckless abandon,” says Mattern.
But internationally, knowledge on how to respond to the virus is growing. Aikman says DoC is in touch with scientists from South Georgia, Falkland Islands, the British Antarctic Survey and the Scientific Committee on Antarctic Research.
It is also participating in groups co-ordinated by MPI that share information on changes in the Antarctic region. “Ongoing contacts between scientists and conservation managers is our best tool to ensure everything is up to date.”
Mattern was in Chile when seabird populations were devastated by the avian influenza in 2023 and predicts we are in for “a pretty depressing period” if it arrives in New Zealand.
“There were dead shags, albatross and penguins washed up on the city beaches, which was pretty hard to stomach.”
He says the penguins were back breeding this summer, although in what appeared to be significantly lower numbers. “They are not gone completely. So, they can recover.”
He suggests what is probably more important than preparing for intervention during an H5N1 outbreak is preparing for the time after. “Because that is where we can actually help our species, by giving them the room and resources to recover.”
Kerrie Waterworth is a science journalist based in Wellington.