In the last three years, a highly lethal form of bird flu has swept across the world, killing birds in Europe, Africa and Asia before leing across the ocean and unleashing worst outbreak of bird flu in American history.
Last fall, the virus, known as H5N1finally arrived in South America.
It raced down the Pacific coast and killed wild birds and marine mammals in astonishing numbers.
Only in Peru and Chile More than 500,000 seabirds and 25,000 sea lions have been recorded dead, according to a new report published last week by OFFLU, a global network of flu experts.
Now, scientists fear the virus will reach the Antarcticaone of the only two continents – along with Australia – that have not yet been affected by the pathogen.
“The negative impact of this virus on Antarctic fauna could be immense, probably worse than on South American fauna,” 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, such as the characteristic emperor penguin and the Antarctic fur seal, agglomerate in large colonies.
“And that could be a recipe for disaster,” said Dr. Ralph Vanstreels, a researcher at a Latin American wildlife health program at the University of California, Davis, and author of the new report.
“We could be facing a very high number of deaths.”
This variant of bird flu, which emerged in 2020, has caused huge outbreaks in poultry farms, killing nearly 60 million farmed birds in the United States alone.
But unlike previous versions of the virus, it has also spread widely in wild birds and has routinely spread to wild mammals.
The virus first peared in South America in October 2022, spreading from Colombia to Chile in just three months.
“As soon as it started moving south, it moved very, very quickly,” said Dr. Marcela Uhart, who directs the Latin American wildlife health program at UC Davis and is an author of the OFFLU report.
It is difficult to estimate the number of victims because many infected animals were probably never detected, according to scientists, and not all dead animals that turned up were tested for the virus.
But in South America, hundreds of thousands of dead seabirds were recorded, including boobies, cormorants and seagulls.
According to the report, the losses accounted for 36% of the Peruvian pelican population in Peru and 13% of the Humboldt penguin population in Chile.
South American sea lions also died in their thousands, representing 9% of the population of Peru and Chile.
(Scientists still don’t know exactly how marine mammals are contracting the virus or whether it is spreading easily among them.)
The virus has continued to move south.
In June, it peared on a South American sea lion off the southern tip of Chile, just 670 miles from the Antarctic Peninsula.
Some birds routinely wander between South America and Antarctica, feeding in both places.
Others will head to their Antarctic breeding grounds come spring in the southern hemisphere, possibly bringing the virus with them.
There has never been an outbreak of highly pathogenic avian flu in Antarctica and its inhabitants likely have few immune defenses against the virus.
“The populations are completely naïve,” says Dr. Thijs Kuiken, a veterinary pathologist at Erasmus University Medical Center in the Netherlands and author of the new report.
“The worrying thing is that the first time it hpens, it will really have a high impact in terms of mortality rate.”
Many of the region’s birds, such as emperor penguins and Cory’s shearwaters, already face other threats, from sources such as climate change, the fishing industry or other human activities.
Some species, such as the Wagtail and the Shag, are restricted to a few islands.
“So if there was an outbreak on those islands, basically the entire species would collse,” Vanstreels said.
Local marine mammals could also be in danger.
Although the Antarctic fur seal has a wide distribution, 95% of the population lives around a single island, making it vulnerable to an outbreak.
Right now, the virus is so widespread that it may not be possible to stop it from reaching Antarctica.
“At the moment, we can’t do anything to prevent it,” says Kuiken.
“So it is important that in the coming months we are as vigilant as possible.”
It will be essential to monitor wild populations to learn more about how the virus is spreading, which species could be most at risk, and what conservation actions may be needed to help them recover, the scientists said.
“What we’re trying to do is document this very well, trying to understand how the virus is moving to see how we can better protect the species in the future,” Uhart said.
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