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Pathogen threat to seabirds

Elephant seals and king penguins on Possession Island, Crozet Islands. Subantarctic islands, like South Georgia and the Falkland Islands, harbour large populations of seabirds and marine mammals. Those species breed in colonies of high density, in which viruses and other pathogens can quickly spread. Credit - Amandine Gamble.

Flight risk: Monitoring avian influenza threats in the Falkland Islands

Since 2021, a highly pathogenic avian influenza (HPAI) virus has been spreading through the world, killing millions of domestic and wild birds, and representing a considerable threat to food safety and biodiversity conservation. Amongst wildlife, seabirds were particularly affected. In Scotland, for instance, it was estimated that 70% of the great skuas might have died of the disease. As it spread through the Southern Hemisphere, there has been growing concerns about the virus reaching Subantarctic and Antarctica, with potentially dramatic effects on the local wildlife, which includes many threaten seabird species. Particular attention has been put on the Falkland Islands, located at the crossroad between South America, Subantarctic, and Antarctica. The archipelago itself is home to exceptional bird communities. It harbours 122 species, including eight globally threatened species and three endemic species. The most emblematic species include albatrosses and penguins.

As part of our project, ‘Pathogens as a threat to seabirds in the Falkland Islands,’ we have been collecting baseline data on pathogen occurrence and contributing to wildlife health surveillance efforts in the archipelago. In the Falkland Islands, one of the rare Subantarctic islands to be inhabited, wildlife health surveillance efforts include systematic site visits led by researchers and conservation officers, but also opportunistic site visits by tourism operators and inhabitants. Inhabitants play a critical role in wildlife health surveillance.

Many Falklanders have seabird and/ or marine mammal colonies on their land and are thus in the front line of the surveillance efforts. They cover large parts of the Falkland Islands territory, broadening more focused surveillance efforts led by research and conservation teams. Any unusual event reported, such as high numbers of sick or dead birds, would trigger an investigation led by the government veterinarians. We can report that no HPAI outbreak has been detected in the Falkland Islands or any other sites monitored by the scientific community across Subantarctic and Antarctica during the 2022/ 2023 austral (southern hemisphere) summer – a summer that turned out to be a ‘usual’ breeding season for local seabirds and marine mammals. The risk of HPAI reaching Subantarctic and Antarctica in the future nevertheless remained high, and our team contributed to wider efforts to assemble risk assessments and guidelines for surveillance and response to a potential HPAI outbreak in the wildlife of Subantarctic and Antarctica.

A skua on New Island, Falkland Islands. Skuas, which are common in the Falkland Islands, are highly impacted by HPAI. A potential explanation is that, as scavengers, they might be highly exposed to the virus when feeding on dead birds and seals. Credit - Amandine Gamble.

While no highly pathogenic variants (usually killing infected birds) of avian influenza have ever been reported from the Falkland Islands, low pathogenic ones (not usually killing infected birds) could have been undetected. Whether it has been present or not can help us assess the risk of HPAI reaching the islands, and the impact it would have. Using the samples our team collected in the field, we explored those questions. We screened the samples for antibodies against avian influenza. If birds have antibodies, it means they have been exposed to avian influenza viruses before and might have some immunity against future exposure to the virus. If birds do not have antibodies, it means they have not been exposed to avian influenza viruses before and have no immunity against future exposure to the virus. Preliminary analyses revealed that very few birds of the Falkland Islands have antibodies against avian influenza viruses, and that a potential introduction of the virus could have dramatic effects on the local birds. On the other hand, it also means that the Falkland Islands are isolated enough to have been spared from the avian influenza viruses, even though they have historically been present in South America and Antarctica.

"As a new breeding season is unrolling, and the outbreak rages in South America, concerns are growing regarding the potential introduction of HPAI to the Falkland Islands."

As a new breeding season is unrolling, and the outbreak rages in South America, concerns are growing regarding the potential introduction of HPAI to the Falkland Islands. Thousands of elephant seals are currently dying from the disease along South American coasts, and just 1,500km away in the opposite direction, in South Georgia, the virus has also arrived, already killing hundreds of seabirds and elephant seals. Back in the Falkland Islands the virus was detected once in a vagrant southern fulmar (Fulmarus glacialoides), though as fulmars do not breed there, it is probable that the bird got infected at another location. Since then, surveillance efforts have been increased, but to much relief, this isolated case does not seem to have sparked local outbreak. The whole local community is keeping a close eye on the health of the wildlife here.

We thank the landowners and caretakers who facilitated sample collection on their land, the Falkland Islands Government Veterinary Services for sharing information on suspected HPAI cases in the Falkland Islands, and all the partners involved in our Darwin Plus project.

Written by Amandine Gamble, Keltoum Boumedjane, and Augustin Clessin. For more information on this Darwin Plus Main project DPLUS167, led by the Institute of Biodiversity, Animal Health and Comparative Medicine at the University of Glasgow, please click here.