Deadly avian flu reaches Galápagos Islands

In a development that has alarmed conservation biologists, the avian flu strain that has devastated birds and marine mammals on five continents has reached Ecuador’s Galápagos National Park, home to species that are found nowhere else.

“It is extremely concerning from a conservation perspective,” says Marcela Uhart, a wildlife veterinarian at the University of California (UC), Davis. “Outbreaks could pose an acute threat to the future of these endemic species.”

So far only a few animals have tested positive for the H5N1 virus, which migratory birds can carry over long distances. But the highly contagious pathogen is likely to spread fast through the Galápagos Islands’ dense colonies of seabirds, seals, and sea lions. Warmer seas caused by an imminent El Niño climate pattern could make species even more vulnerable by depleting the ocean life that sustains them. Park authorities are already restricting access to some areas to prevent accidental spread of the virus, raising concerns among residents that outbreaks could depress the tourist economy.

The H5N1 virus has circulated in Europe, Africa, and Asia for decades, sometimes causing large losses of poultry. In late 2021, a new, especially aggressive subvariant appeared in North America and soon spread—for the first time—to South America. In the Galápagos, “We were just waiting, wondering when is [an outbreak] going to happen?” says Gustavo Jiménez-Uzcátegui, a wildlife veterinarian with the Charles Darwin Foundation.

Last week, tourist guides noticed dead seabirds, including frigatebirds and red-footed boobies, on two islands in the archipelago. Park rangers and technicians from Ecuador’s Galápagos Biosecurity Agency collected five carcasses: three tested positive. “We know this is the tip of the iceberg,” Jiménez-Uzcátegui says. “We have eyes watching the whole archipelago,” including park rangers, researchers, and tourist guides.  

Biologists have not yet identified which variant infected the birds. But it is likely 2.3.4.4b, the new highly pathogenic variant, says virologist Thijs Kuiken of Erasmus University Medical Center. That strain “is raging through South America,” says wildlife virologist Wendy Puryear of Tufts University. Farmers have been ordered to kill millions of infected poultry, and sea lions and fur seals have been hit hard in Peru, Chile, Argentina, and Uruguay.

The virus could have reached the Galápagos with a migrating bird, or when seabirds living there encountered infected birds while foraging close to the mainland, says Ralph Vanstreels, a seabird specialist at UC Davis. In May, he notes, a dead waved albatross, a critically endangered species that breeds in the Galápagos, tested positive for H5N1 in Peru.

Managers have few options for slowing H5N1’s spread. Removing carcasses quickly appears to have helped in some outbreaks elsewhere, Puryear says. And because the virus can be spread on shoes, park authorities have already closed visitor sites on Genovesa and San Cristóbal islands where dead birds were found. They have also closed two important breeding colonies on Española Island, even though no birds have tested positive there. Jiménez-Uzcátegui thinks visitors should be temporarily banned from other key breeding sites, too.

Researchers studying the colonies are also taking precautions, including keeping their distance from the birds. Park and biosecurity officials will be meeting with universities and others to coordinate monitoring and research efforts. The California Academy of Sciences is trying to figure out how the situation will affect an expedition to Floreana Island planned for November, although a large annual survey of Galápagos seabirds and sea lions is still scheduled for that month.

One continuing concern is that the virus will jump from species known to be susceptible, such as gulls, to others so far less afflicted. The 18 species of Galápagos finches made famous by Charles Darwin, for example, live in close contact with large seabird colonies.

Disease is not a common cause of extinction, but contagious pathogens can push small populations to the point of no return, Kuiken says. Extinction risk is higher for species that only occur in one place, such as the Galápagos lava gull—the world’s rarest gull with just 300 breeding pairs. The Galápagos penguin is also only found on the islands, but it is related to the Humboldt penguin, which has had high mortality from H5N1 in South America.

The coming El Niño event is adding to concerns. El Niño often disrupts populations of fish, squid, and other prey sought by penguins, cormorants, and sea lions, and food shortages can weaken immune systems and make animals more susceptible to disease. Luckily, this El Niño is not forecast to be especially severe, and penguin and cormorant populations are robust after 3 years of a La Niña weather pattern, which brought abundant prey.

To help reduce stress on species facing outbreaks, Uhart says, managers should step up conservation efforts, such as by reducing fisheries bycatch and preventing unregulated tourism. “Affected wildlife will need all the help we can provide.”

Jaime Chaves, an evolutionary biologist at San Francisco State University who has studied birds on the Galápagos Islands for more than a decade, is coping with his worries by planning research. The Galápagos have always been a laboratory of evolution, and he wants to monitor how the virus, too, evolves there. “Evolution,” he says, “is taking its course yet again in this new setting.”

In the short term, however, that’s not much consolation.