Bird flu has crept uncomfortably close to home in recent months. Public health experts have detected nearly five dozen known infections of the H5N1 avian influenza virus in people in the U.S. Dairy farmers are approaching a full year of exposure to the virus in their herds. And more than 100 million birds in U.S. poultry farms have been lost to the pathogen or killed in attempts to stop its spread since February 2022.
Meanwhile the type of H5N1 virus that has been spreading, known as clade 2.3.4.4b, has also infiltrated ecosystems around the world, wreaking devastation that has mostly gone overlooked. Millions of individual wild animals belonging to hundreds of species—wild parakeets and penguins, otters and owls, ducks and dolphins—have died on every continent except Australia, including in some of the most pristine places scientists monitor. Understanding the true scale of avian influenza in the wild is more a matter of guesswork compared with scientific estimates of its impact on domesticated species.
“Wild birds often die in inconvenient places, and it requires people’s time to respond to these, or to count these,” says Michelle Wille, a disease ecologist at the University of Melbourne. “In contrast, farmers usually have detailed numbers of poultry in their sheds. So it’s about effort.”
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
Where that effort has been made, the results have been grim, revealing a wave of death caused by H5N1 across the globe. In South Africa in 2021 monitors counted 20,686 dead Cape Cormorants that were infected with bird flu. At breeding sites across northwestern Europe in 2022 scientists tallied 16,873 dead adult seabirds called Sandwich Terns. Twenty-one massive California Condors—precious individuals in a population of fewer than 600 animals—died in Arizona and Utah in early 2023. At certain Argentine beaches later that year as many as 96 percent of elephant seal pups died, suggesting the region’s total death toll may have been more than 17,000 animals.
Those elephant seals marked a particularly concerning pair of developments. They were proof both that the virus was able to impact mammals in large numbers and that it was fast approaching the Antarctic region, home to some of the most stunning ecosystems and beloved animals on Earth.
“As it continued southward and got into South America, that, for us, was really the time when alarm bells were going off,” says Ash Bennison, a marine ecologist at the British Antarctic Survey, who says he started worrying about H5N1’s threats to the region at the beginning of 2022, nearly two years before the virus reached the Antarctic.
One area of concern was the island of South Georgia, a rugged, wildlife-filled landscape located some 900 miles off the tip of the Antarctic Peninsula that is surrounded by several smaller islands. “It’s often described as being the Alps coming straight out of the water,” says Mark Belchier, a marine fisheries ecologist at the British Antarctic Survey and director of fisheries and environment for the government of South Georgia and the South Sandwich Islands. “As the only dry land for many hundreds of miles, it’s a key haul-out spot for breeding.” Several species of whale feast in its rich waters, while three species of seals and four species each of penguins and albatross breed on the island, crowding along the coastline. Tourists with the means to reach the remote island flock to it as well. In the most recent year with data available, more than 26,000 people—including tourists, scientists and support staff—visited South Georgia.
One of those people was Theo Allan. Trained as an architectural photographer, he made the pivot of a lifetime in 2019 when he turned his camera to document Antarctic tourist expeditions. “It’s almost like going to Mars, where you don’t have any form of human civilization and nature takes its course,” Allan says. “The size of these icebergs makes you feel like an ant.”
During excursions from cruise ships, he and tourists climb into inflatable boats to approach the shore, darting among icebergs that could collapse at any moment. Even under the best of conditions, the work is strenuous. “The wind is blowing; [there are] snowflakes, sheets of snow hitting your face,” he says. “It can get quite intense.”
The conditions were still more difficult when he reached South Georgia in January 2024 for a visit of some two and a half months. That’s when he saw evidence that avian influenza had beaten him to the region.
Two skuas feeding on a penguin carcass, highlighting the role of the Antarctic food chain in the transmission of avian influenza.
Theo Allan
The first known cases around South Georgia were found in seabirds at Bennison’s home base of Bird Island, off the western tip of the main island. (Although it’s possible that humans could have brought the virus to Bird Island, scientists say the evidence suggests migrating animals were the more likely vector.) In mid-September researchers saw a young Southern Giant Petrel that appeared sickly shortly before its death. By early October, they started seeing dead Brown Skuas. Both species are predators and scavengers—scientists had reported Brown Skuas feasting on the corpse of the strange-looking petrel. As the virus spread, the petrels were mostly spared, but dozens of the skuas were found dead. Scientists know that scavenging on sick animals can transmit avian influenza between species, but Bennison says it isn’t clear why the petrels weathered the illness.
“They’re animals that scavenge on very funky carcasses of things like elephant seals, fur seals, so they’re probably exposed to a huge range of pathogens already,” he says of the petrels. “It might be that there are certain animals with certain ecologies, and that can kind of mean that they have a heightened immune system or perhaps a more relaxed immune system.”
But the skuas were just the beginning. Bennison and his colleagues also tallied Gentoo Penguins, Wandering Albatross and fur seals dead or dying on Bird Island and South Georgia proper. Where they could, the scientists swabbed the corpses and shipped samples back to the U.K. for testing, which eventually confirmed that many of the animals had avian influenza.
The region is no stranger to wildlife carcasses. “There’s always dead and dying animals,” says Sally Poncet, an independent ecologist, who has worked on South Georgia for decades. “That’s what South Georgia is all about; it’s all about life and death.” But she noticed that after avian influenza arrived, the bodies piled up faster than usual.
King Penguins waddling past the rotting carcass of an adult fur seal at South Georgia Island, part of the British Overseas Territory of South Georgia and the South Sandwich Islands, in the Antarctic.
Theo Allan
Allan saw the difference as well when he arrived in January and began visiting familiar locations. Although he was expecting to see the virus’s effects, it was a little bit of a “numbing experience,” he says, to “see these animals pretty much dead on the entire shoreline amidst other living animals who are pretty much going to die as well. I don’t know how to put it into words, but it’s hard to witness.” He smelled the difference, too. “When I was in close to some of these carcasses, the stink was very heavy in the air,” Allan says.
Allan was also struck by watching the survivors seem to grapple with the deaths of their neighbors. For him, the most powerful moment of the season came as he watched a group of King Penguins waddle inland from the coast. One bird peeled off from the group to stand next to the carcass of another penguin. “The group kept walking. And then the entire group turned around and looked at this one penguin standing next to the carcass,” Allan says. “It felt very humanlike.” He was particularly reminded of the darkest days of the COVID pandemic, which he spent in India. “Loved ones wouldn’t touch their own relatives,” he says. “Some of them wouldn’t even go to collect the bodies from the hospital.”
A group of penguins distance themselves from the carcass of another penguin while one among them stops waddling and stands next to the carcass.
Theo Allan
Scientists working to understand avian influenza and its impacts on wildlife have also been forced to confront the emotional reality of the dead and dying. “Knowing that there was very little you could do to minimize any sort of transmission or threat to these animals is quite sad,” Bennison says. “What you have to do is buckle in and put your little scientist hat on and try really hard to collect the data to make it worthwhile to the animals.”
This year scientists will be able to collect even more data and process them more quickly. That’s because a team of researchers including Amandine Gamble, an ecologist at Cornell University, is in the region to test samples for bird flu directly on South Georgia, for example, instead of relying on laboratories an ocean away.
That testing includes not only diagnosing avian influenza but also understanding questions such as whether animals are developing resistance to the virus. If they are, the finding would raise hopes that last season’s deaths would be an anomaly rather than a permanent threat. Gamble says that her initial sense is that scavengers may be developing resistance but that this is not the case for the Gentoo Penguins that were last year hit both on South Georgia and on the Falkland Islands, closer to South America.
Allan is back in the south, watching how the situation unfolds. So far scientists have hints that the wildlife of South Georgia and its surrounding islands are faring better this year than they did last year. Bennison says that as of the end of October, he and his colleagues had spotted two suspicious dead skuas—compared with around 50, accompanied by Gentoo Penguins, at the same time last year. Many of the island’s nesting birds have already laid eggs, and seals are returning to establish their territories for breeding, he added. Early reports from this season in South America’s elephant seals, however, suggest that breeding populations this year could be much smaller than usual.
A Black-browed Albatross skull, likely remnants of last year's avian influenza outbreak, seen on the Falkland Islands.
Amandine Gamble/Cornell University College of Veterinary Medicine
The scientists say avian influenza could affect a different suite of species this year, leaving open the possibility that more death could still be in South Georgia’s future. In addition, southern outposts that dodged avian influenza last year, such as Antarctica proper, may find their luck running out in coming months.
Still, Belchier is taking hope from the fact that last year’s deaths came primarily in juveniles rather than adults across the age spectrum. “These are species that often deal with boom-and-bust-type situations in the environment,” he says. Their populations are structured so that one bad year of breeding doesn’t wipe out the species. Gamble notes, however, that she and her colleagues are seeing dead adult Gentoo Penguins on the Falkland Islands, which may suggest a longer-term issue for the population.
Even when it comes to more dramatic losses, South Georgia has a history of resilience, Poncet says. Humans slaughtered countless seals and whales and introduced rats that wreaked their own devastation on local wildlife. Each time, with human cooperation, species have bounced back. “South Georgia’s wildlife has seen it all already,” she says.
“It’s incredibly resilient,” Poncet says. “Hopefully they’ll cope. Wildlife usually does, if we leave it alone.”