The recent detection in Antarctica of the sometimes highly pathogenic H5 subtype of avian flu in Adélie penguins (Pygoscelis adeliae), Antarctic cormorants (Leucocarbo bransfieldensis) and south polar skuas (Stercorarius maccormicki) has fanned fears of significant animal deaths there.

The findings have also stirred concerns about continued worldwide propagation and spread of the avian influenza, which has pummeled bird and marine mammal populations around the world, particularly in South America along the continent’s migratory bird routes.

A study published in the March edition of the journal Emerging Infectious Diseases says 26 countries found H5 infection in at least 48 mammal species from 2020 to 2023. Most were terrestrial, but some were marine mammals, with sea lions hit particularly hard in Peru, Chile and Argentina. In March 2023, Chile reported 1,535 sea lion and 730 penguin deaths from avian flu up to that point in the year, while Peru said 3,492 sea lions had been killed by the virus in 2022.

“The geographic area and number of species affected [during 2020-2023] by the current event are considerably greater than in the previous waves of infection [from 2003 to 2019],” says the study.

The study also warns that the current bird flu outbreak might surpass earlier ones in terms of economic losses, geographical scope, and the numbers of species and individual animals that are infected.

So far, though, the epizootic has not affected Ecuador’s world-renowned Galápagos Islands as much as had been feared.

This March, scientists on the archipelago sounded the alarm over seabird deaths at Fernandina Island’s Punta Espinoza and Isabela Island’s Bahía Urbina. The discovery fueled concern that the H5 bird-flu subtype was spreading on the archipelago, prompting Galápagos National Park to close both areas to tourists. Tests proved negative for bird flu, however, and both sites were reopened two days after the closure had been declared.

Protocols applied

In its response, the park was following protocols established last September after the H5 bird-flu subtype was found to have caused bird deaths at two islands on the eastern side of the Galápagos chain—San Cristóbal and Genovesa. The specific locations—Punta Pitt and the islet of Lobos at San Cristóbal, and Darwin Bay at Genovesa—were closed to tourists and targeted for monitoring and various protocols to prevent spread.

Darwin Bay remains closed due to positive follow-up tests. But tests in December at Punta Pitt and Lobos found no bird flu, so those two sites could be reopened in April if additional tests conducted in late March are negative, Mariuxi Farías, who oversees public use of Galápagos National Park, tells EcoAméricas.

“The epidemiological regimen as well as strict biosafety protocols and monitoring have helped contain and prevent the spread of the virus,” Farías says. “We have adopted a series of measures to prevent species from being affected, especially the archipelago’s emblematic and endemic ones,” such as Galápagos flightless cormorants (Phalacrocorax harrisi) and Galápagos penguins (Spheniscus mendiculus).

As of late March, the deaths of some 400 Galápagos birds of various species had been reported since September, though it had not been determined how many of them were victims of the bird-flu virus. The species included the red-footed booby (Sula sula), blue-footed booby (Sula nebouxii), Nazca booby (Sula granti), great frigatebird (Fregata minor) and swallow-tailed gull (Creagrus furcatus).

Scientists and park authorities agree, however, that bird-flu has taken a relatively low toll on the islands—so far, at least. “It seems that there is something protecting the archipelago,” Carlos Valle, a seabird expert and professor at San Francisco University of Quito, tells EcoAméricas. “We expected a very strong impact. Fortunately, the Galápagos have been lucky and the onslaught of influenza has not been greater. Possibly the [H5] variant that reached the islands was not very aggressive.”

Gustavo Jiménez, principal seabird researcher at the Charles Darwin Foundation, says the currently ongoing El Niño weather pattern might account for the relatively minor bird-flu impact on the islands thus far.

Moderated by El Niño?

Species isolated on island chains tend to be more vulnerable once exposed to emergent illnesses such as bird flu, Jiménez acknowledges. But he says elevated sea temperatures caused by El Niño in the eastern Pacific Ocean might have inhibited the virus because avian flu is more active in cold-water environments. Jiménez says he is currently working to test this hypothesis involving El Niño, which is expected to begin to dissipate in June.

For his part, Valle says the danger for the Galápagos is latent, warning that it could only be a question of time before the virus reaches western Galápagos islands of Fernandina and Isabela. These islands are the object of special concern because they’re home to small and thus fragile populations of endemic seabirds including penguins and flightless cormorants.

The two western islands are also home to the archipelago’s main colonies of Galápagos fur seals (Arctocephalus galapagoensis). Though so far no Galápagos mammals have tested positive for avian flu, experts are mindful of the risk faced by these animals and by land birds such as the islands’ endemic finches.

Last December the UN Food and Agriculture Organization’s regional office for Latin America and the Caribbean forecast that avian flu this year could equal or exceed its levels last year. An estimated 12.5 million wild and farm-raised birds died or had to be killed to curb the spread of the disease. Valle recommends preparing for the worst: “It’s time biologists in different specialties and veterinarians work together as we’ve done in the Galápagos so we’re ready to act if eventually there’s a massive die-off.”