For the past three years, a highly deadly strain of avian flu has spread around the world, felling birds in Europe, Africa and Asia before leaping across the ocean and sparking the worst avian flu outbreak in United States history .
Last fall, the virus known as H5N1 finally arrived in South America. It swept quickly along the Pacific coast, killing wild birds and marine mammals in staggering numbers. Peru and Chile alone have reported more than 500,000 dead seabirds and 25,000 dead sea lions, according to a new report, published last week by OFFLU, a global network of flu experts.
Now scientists fear the virus will make its way to Antarctica, one of only two continents — along with Australia — not yet affected by the pathogen. “The negative impact of this virus on Antarctic wildlife could be enormous – probably worse than that on South American wildlife,” the report warns.
More than 100 million birds breed in Antarctica and nearby islands, and many marine mammals swim in the surrounding waters. Some of these species, including the distinctive emperor penguin and the Antarctic fur seal, crowd into large colonies. “And that could be a recipe for disaster,” said Dr. Ralph Vanstreels, a researcher at a Latin American natural health program at the University of California, Davis, and an author of the new report. “We could face a very high death toll.”
This variant of bird flu, which emerged in 2020, has caused massive outbreaks on poultry farms, resulting in nearly 60 million farmed birds in the United States alone. But unlike previous versions of the virus, it has also spread widely among wild birds and has been routinely transferred to wild mammals.
The virus first appeared in South America in October 2022 and spread from Colombia to Chile in just three months. “Once it started moving south, it happened very, very quickly,” said Dr. Marcela Uhart, who directs the Latin American Natural Health Program at UC Davis and author of the OFFLU report.
The number of victims is difficult to count because many infected animals were probably never discovered, scientists say, and not all of the dead animals that have turned up have been tested for the virus. But hundreds of thousands of dead seabirds were reported in South America, including boobies, cormorants and gulls. According to the report, the losses accounted for 36 percent of Peru’s population of Peruvian pelicans and 13 percent of Chile’s Humboldt penguins.
South American sea lions also died in their thousands, representing 9 percent of the population in Peru and Chile. (Scientists still don’t know exactly how marine mammals contract the virus and whether it spreads easily among them.)
The virus has moved further south. In June, he turned up in a South American sea lion in the very south of Chile, just 1,000 kilometers from the Antarctic Peninsula. Some birds routinely wander between South America and Antarctica, feeding in both locations. Others will make their way to their Antarctic breeding grounds as spring arrives in the southern hemisphere, possibly bringing the virus with them.
Antarctica has never had an outbreak of highly pathogenic avian flu before, and its inhabitants probably have little immune defense against the virus. “The populations are completely naive,” says Dr Thijs Kuiken, a veterinary pathologist at the Erasmus University Medical Center in the Netherlands and author of the new report. “The concern is that the first time it goes ahead, it’s going to have a really big impact in terms of mortality rate.”
Many of the region’s birds, including emperor penguins and sooty petrels, are already facing other threats, such as climate change, the fishing industry or other human activities. Some species, such as the southern pintail and the Macquarie cormorant, are confined to only a few islands. “So if you were to have an outbreak on those islands, basically the whole species collapses,” said Dr. Vanstreels.
Local marine mammals may also be at risk. While the Antarctic fur seal may have a wide range, 95 percent of the population lives around just one island, making it vulnerable to an outbreak.
At the moment, the virus is so widespread that it may not be possible to prevent it from reaching Antarctica. “At this point there’s nothing we can do to prevent this,” said Dr. Jugs. “It is therefore important to be as alert as possible in the coming months.”
It will be critical to monitor wild populations to learn more about how the virus is spreading, which species are most at risk and what conservation measures may be needed to help them recover, scientists said. “What we’re trying to do is document this very well, try to understand how the virus moves to see how we can better protect the species in the future,” said Dr. Uhart.
