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South Africa, Our Burning Planet

SA unveils biosecurity plan after avian flu ravages Marion Island

SA unveils biosecurity plan after avian flu ravages Marion Island
A crowd of king penguins at Marion Island. (Photo: Tiara Walters)
Tiara Walters
By Tiara Walters
24 Mar 2025
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The virus has claimed 150 wandering albatross chicks, but adults in other species are a bigger concern, says the Department of Forestry, Fisheries and the Environment. For now, it is cautiously optimistic about local seal populations.

At least six bird species on Marion Island, South Africa’s biodiverse sub-Antarctic territory, have been infected with deadly H5N1 avian flu. 

Following Daily Maverick’s revelations last week that the virus had been confirmed in a Western Cape government report, the national Department of Forestry, Fisheries and the Environment issued a statement at the weekend flagging deaths among seabirds. 

“Samples collected between September and December 2024 were all shipped back to mainland South Africa, via the SA Agulhas II, in February 2025,” says the department.

King penguins, wandering and sooty albatrosses, brown skuas as well as southern and northern giant petrels have been affected. 

At least 150 of about 1,900 wandering albatross chicks “from the 2024 cohort” have died as a result of the killer H5N1 virus, a type of highly pathogenic avian influenza (HPAI). 

This is worrying, as the island group hosts nearly half the world’s breeding population of wandering albatrosses. 

However, adults have borne the brunt of the recorded impact in other species: about 120 adult king penguins and “at least” 80 adult brown skuas have died.

“The deaths of adult seabirds are of greater concern than chicks, because most species only start to breed at three to ten years of age, and most affected species raise at most one chick per year,” the department explains. 

A crowd of king penguins at Marion Island. (Photo: Tiara Walters)


‘Reduced mortality rate is promising’


A significantly smaller number of deaths have been observed in the two reported petrel species: at least 24. Five sooty albatross deaths have been recorded.

After an initial suspected case in a brown skua, recorded in mid-September 2024, “more similar cases were reported in early November and mortalities in multiple species have continued into March 2025, though the overall death rate slowed significantly in January”. 

The “reduced mortality rate is promising”, the department points out, but the problem with Marion is that more than 30 bird species breed there.

“The bird species and age composition varies throughout the year, therefore it is difficult to predict how the outbreak will progress,” the department cautions. 

Biodiversity under fire


Found 1,700km southeast of Cape Town, and halfway to Antarctica, Marion’s seabirds face other threats, including “fisheries bycatch, climate change, plastic pollution and predation by introduced house mice”. 

According to photos published in a new study led by the University of Cape Town and the South African National Biodiversity Institute, the warming island is also in the firing line of an army of advancing plants.

Marion, the study notes, has weathered “significant vegetation change, showing a greening trend across most habitats in the last five decades”.

The potential effects of the virus on large numbers of southern elephant seals, as well as sub-Antarctic and Antarctic fur seals, “are also of concern but no increased mortality has been reported in any mammal species so far”.

Inferring impacts at Prince Edward


To help protect its ecological value, access to Marion is tightly controlled. 

Tourists are not allowed and only permitted government invitees and station researchers are approved.

So, what about the virus’ impact at neighbouring Prince Edward Island — the more tightly controlled South African territory that limits visits to one every four years? 

“Observations of and laboratory test results for HPAI/H5N1 on Marion Island can assist in inferring the potential risk to animals on Prince Edward Island, since they share various ecological characteristics,” says the department. 

In other words, though the potential impact is uncertain, Marion could paint a picture of what is happening at Prince Edward. The last survey was undertaken in November 2023 and no suspected infiltration was reported at the time. 

Swift, devastating toll


Since 2003, the virus has become better adapted, ripping across 6,000km of South America from 2022.  

The British Antarctic Survey’s confirmation of the virus in brown skuas on South Georgia in October 2023 was a historic warning that the sub-Antarctic region’s far-flung ecosystems were no longer safe — or even that remote. 

In February 2024, a Spanish-Argentinian collaboration confirmed the virus, which can be transported across vast distances by bird migrations, in Antarctica for the first time ever. 

Last month, the Spanish Research Council reported that mainland Antarctica was reaping a grim toll: “H5 influenza virus was detected in 50% of the carcasses tested, which strongly suggests that the virus is causing significant mortality in various species in the Antarctic Peninsula, especially skuas.”

Humans may also act as possible vectors, inadvertently spreading the virus between wildlife colonies.

“In many cases the viral load in dead animals was very high, indicating a potential risk of exposure to the virus in the proximity of the carcasses,” said the council.

The virus was also detected at the French archipelagos of Crozet and Kerguelen — 950km and 2,300km east of Marion, respectively — in October and November 2024.

South Africa releases its biosecurity protocol


Daily Maverick has repeatedly requested the opportunity to review and report on the national government’s H5N1 biosecurity protocol, which the department describes as a “living document, undergoing periodic revisions based on national consultations and alignment with international best practices”. 

In its latest statement on the virus, the department has publicly released a 25-page protocol, which was initially finalised for implementation in the first quarter of 2024.

“The HPAI protocol that has been implemented on Marion Island was developed by the Department of Forestry, Fisheries and the Environment, the management authority for the Prince Edward Islands, together with Western Cape Veterinary Services, marine ornithologists, marine mammal biologists, disease experts and colleagues overseas with similar experience,” it says. “Efforts to monitor and hopefully limit the spread of the virus on the island will continue.”

It adds that the “situation on Marion Island is being closely monitored by the field personnel overwintering on the island, who have been trained to recognise possible HPAI signs in birds and seals, and in the necessary monitoring and mitigation methods”. 

“They will continue to take all precautions to ensure they do not spread the virus. There are few other disease mitigation tools available in this type of situation.” 

Dr Michelle Wille of the Antarctic Wildlife Health Network previously told us about the virus’ spread in Antarctica: “I think we are all collectively struggling with ecological grief and are speaking as loudly as we can.” 

The network is an initiative of the Scientific Committee on Antarctic Research. 

“It has been very challenging to convey the level of mortality to the public,” said Wille, “as well as the implications of these mortality events. Scientists are speaking widely to media outlets as best as possible.” DM

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