A new kind of death is coming to Antarctica, scientists fear. The harsh environment is full of everyday heartbreak: predation, famine, chicks lost at sea as their icy coastline melts away. Now a new pathogen threatens to wipe out colonies of marine mammals and birds, including possibly penguins. If the worst happens, ghosts of entire species could emerge – and there’s little scientists can do but wait.
A deadly strain of H5N1 bird flu is sweeping through poultry farms and flocks of wild birds around the world, infecting mammals and even killing at least one polar bear. Now it’s knocking at Antarctica’s gates, just as dozens of species that have probably never experienced any form of bird flu are coming together to raise their next generation. Bird flu is currently causing major outbreaks on islands around the southern tip of South America, about 1,000 miles (1,600 kilometers) from the Antarctic Peninsula. The virus led to disease clusters in gentoo penguins on the Falkland Islands in January and in fur seals, elephant seals and other animals on South Georgia Island last December. Scientists fear the virus only needs a short hop to reach the Antarctic Peninsula and spread to the rest of the continent.
“We are somewhat prepared for impact. We have been that way since the end of [last] years,” said Marcela Uhart, a wildlife veterinarian at the University of California, Davis, who is currently monitoring the outbreak from Patagonia. “It’s unlikely [avian influenza] won’t get there just because of the closeness of the species,” with the animals often traveling long distances through the Southern Ocean to find food.
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Bird flu comes in two variants. Typically, wild birds contract mild cases of what scientists call “low-pathogenicity” flu, while farmed poultry species such as chickens and ducks can develop much more serious infections with “high-pathogenicity” strains. These different flavors can mix, creating more contagious viruses, such as the one currently ravaging South America. That combination, a subtribe called clade 18.104.22.168b that has evolved over the past decade, comes from a lineage identified in China in the mid-1990s that has led to occasional outbreaks around the world. But clade 22.214.171.124b has now become a Frankenstein virus that combines severe disease of poultry strains with a particular affinity for infecting wild birds. The virus has not only struck South America, but has devastated seabird colonies in Europe, followed migratory birds south to Africa and jumped across the Atlantic Ocean to infect even the regal California Condor.
“Bird flu is nothing new; it’s been around for a long time,” said Christian Walzer, a wildlife veterinarian and executive director of health at the nonprofit Wildlife Conservation Society. But this bird flu is different. “What’s important to understand is that the whole dynamic has changed,” he says.
Despite the rapid spread of this species, scientists are not sure how it is transmitted between animals, and especially not how it spreads between birds and mammals. Many infected species are scavengers, suggesting that consumption of infected corpses could contribute to transmission; healthy animals can also pick up the virus from the feces of infected animals, researchers say. Some species appear resistant to disease, although they can still contribute to transmission. “The big problem we have is: we don’t really understand how some birds can become infected with this virus and not get sick, but it’s clear that they do,” said Ashley Banyard, a virologist at the UK Animal and Health Agency. plant health.
By late 2022 and early 2023, the brutal clade 126.96.36.199b virus had killed at least 600,000 birds and 50,000 mammals in South America — and likely many more, scientists say. “We’ve never had anything of this magnitude in the Southern Hemisphere,” Uhart says.
Antarctica and Australia are currently the only continents this bird flu has yet to reach – as far as scientists can tell. Especially for Antarctica, the virus can simply spread unnoticed. “There’s no way to know for sure,” says Michelle Wille, a viral ecologist at the University of Melbourne in Australia who focuses on bird viruses. “One of the big challenges is that it could already be there, in a place where few people go.”
Detecting a wildlife infection in a remote location is difficult work, but especially so when most of the victims are ocean-based species. “It’s very difficult to detect anything at sea,” says Amandine Gamble, an ecologist at Cornell University. “It is probably a huge underestimate of the actual number of fatalities.”
Scientists are concerned that if the virus becomes established in Antarctica, there will be a particularly high number of victims on the continent. “Highly pathogenic bird flu has never been observed there before,” says Thijs Kuiken, a pathologist at the Erasmus University Medical Center in the Netherlands. “The majority of the 48 species of birds and 26 species of marine mammals present in Antarctica are likely susceptible to infection and disease from this virus.”
These animals are not only immunologically vulnerable, but they also have a lifestyle that puts them at additional risk of infection. “You have these huge, densely packed bird colonies and some of these mega-charismatic, highly endangered species, all packed in there,” Walzer says, like penguins. “Like [the virus] If it does happen, the consequences will be potentially very devastating.”
“Entire populations can disappear,” says Wille about a possible outbreak in Antarctica. “This would be a catastrophe.”
It could be a catastrophe for species beyond those directly affected — and even for the species that call Antarctica home, Uhart says. For example, if there is a mass death event on the continent, and these corpses become encased in ice instead of sinking into the ocean, the deaths could potentially affect the global carbon cycle and the flow of nutrients. “I don’t think anyone can even imagine what the loss of this potentially enormous wildlife biomass would mean for the ocean,” Uhart says. “I don’t think we understand what this means.”
Timing could affect how bad an outbreak of bird flu in Antarctica could be, experts say. Currently, the continent is in the height of summer and many species are still raising their young – whose new immune systems could be more susceptible to bird flu or more likely to spread it, scientists say. “This is a crucial phase,” says Gamble.
“If it actually reaches now, it could spread very, very quickly,” she says. “If we manage to keep the virus from reaching the Antarctic continent for a few more weeks, we might be safe for this year.” Most species will disperse from tightly packed colonies until the next breeding season, making them less likely to encounter other animals – and therefore the virus. Still, Gamble and others worry that this would likely only be a temporary reprieve, given how aggressively the virus is circulating worldwide. Antarctica may avoid the crisis this year, but will suffer during next Southern Hemisphere spring and summer.
Like many ecological disasters, the story of bird flu highlights the consequences of human disruption of the natural world, scientists say. Modern poultry farming, where birds are packed together even more densely than the busiest penguin colony, promotes the spread of disease. And while several bird flu vaccines exist, countries around the world have typically opted to kill a farm’s entire population after exposure instead. In the US alone, tens of millions of chickens have died or been culled since 2022. That decision was prompted by fears that vaccinated chickens would disrupt international trade because tests cannot distinguish between infected and vaccinated birds. Countries that do not vaccinate will not import poultry with a positive bird flu test.
And now, Uhart says, it’s sea lions and elephant seals, cormorants and pelicans and, yes, even penguins that are suffering from this virulent virus. “These poor animals die without a voice,” she says. “Unless we tell their story, it could very well remain untold.”