Bird flu is spreading in Antarctica and threatening rare species there

Highly contagious avian influenza has moved to Antarctica. Which The British Antarctic Survey (BAS) reported The beginning of this week. The agency found many dead and seriously ill seabirds on Bird Island, off the larger island of South Georgia, under South America. This concerns the now infamous H5N1 variant that has been spreading around the world since 2021 and causing large numbers of casualties among wild animals.

The only birds affected so far are the great subantarctic jays (stercorarius antarctica). They are large brown seabirds closely related to gulls and terns. They migrate annually from their breeding grounds in Antarctica to their wintering grounds further north and return in the spring (our fall). The great hunters of Bird Island likely contracted the virus in South America, where bird flu arrived at the end of 2022 and has been hitting hard ever since.

“It was expected that the virus would reach Antarctica,” says Theis Kuijken, a bird flu expert from the Erasmus MC Center in Rotterdam. “But if it actually happens, it will come as a shock. Really bad.”

The risk of contamination is high

Bird Island and South Georgia are home to tens of millions of seabirds, including albatrosses and penguins. Just On Bird Island itself It’s about 50,000 pairs of penguins. In addition, 65,000 sea lions live there, and they are also highly vulnerable to bird flu. “There’s a good chance this will become a major outbreak,” Kuykin says. “The great hunters are predators and scavengers: they visit all those other species. Huge risk of contamination.” In addition, large SKUs live along the edge of the entire continent; They can cover great distances, especially with the wind at their backs. They can therefore also transmit the virus to other parts of Antarctica.

Avian influenza viruses have always been around. Every now and then, through mutations and mixing with other influenza viruses, variants emerge that are more dangerous than others. Variants that make poultry seriously ill are called highly pathogenic. Over the past 25 years, there have been regular outbreaks in Europe of highly pathogenic variants that originated in poultry in Asia and were spread by migratory birds. But previously it always involved seasonal disease outbreaks.

However, since October 2021, an H5N1 strain has been circulating, originating from southern China, which no longer disappears in the summer. As a result, large numbers of breeding birds are now infected; In the Netherlands, among others Black-headed gulls, Tern sandwich And also Sea eagles.

Dead sea lions

“This is the largest outbreak of animal disease that I know of,” Kuiken says. “The numbers are staggeringly high, especially in South America. This year alone, about 20,000 marine mammals, mostly sea lions, and more than half a million seabirds have died there. We know that Antarctic migratory birds spend the winter there as well.

Where will this end? “This could be a death blow for rare species that live only on the islands around South Georgia,” Kuyken says.Including species of ducks, cormorants and Antarctic terns. The same applies to the islands on the New Zealand side of Antarctica. It is believed that penguins will not become extinct anytime soon, because most species are so numerous. “Eventually a balance will be established, because some immunity will arise. But in such cases we often see a lot of deaths among young people every year. Therefore, the virus will undoubtedly continue to have a suppressive effect on the population.”

There is no significant direct risk to humans, according to the virologist: in Antarctica, there is little interaction between people and birds. “But there are millions of sea lions living close together. If they become infected en masse, there is a risk of mutations that make the virus more dangerous to mammals.