Nature / Around 1,500 dead bonxies found in Foula last summer
ROUGHLY 1,500 dead bonxies were found in Foula last summer amid the bird flu outbreak, a report has revealed.
The study also highlights a 60 to 70 per cent decline in bonxies – or great skuas – in occupied territories on the island.
Meanwhile government data shows the bird flu strain H5N1 was found in otters last year, including one in Shetland.
There is now evidence of at least 200 cases of bird flu infection in mammals worldwide, and experts are said to be “acutely aware” of the risks of avian flu becoming a pandemic.
The contagious bird flu virus had a massive impact last year, leading to significant numbers of fatalities among a range of sea birds including in Shetland.
The breeding population of bonxies at the Noss National Nature Reserve fell by nearly 80 per cent last year, for instance.
The figures from Foula – which has a population of around 30 people – are contained in reports authored by marine ecologist Kees Camphuysen of the Royal Netherlands Institute for Sea Research and local ranger Sheila Gear.
One report said there were “exceptional mortality levels, poor reproductive success and a major population decline” in bonxies breeding in Foula.
Searches carried out between May and September found 1,501 corpses, of which around 110 had previously been ringed. More than 40 dead northern gannets were also recorded, while some other birds were also found.
Clusters of bonxies were found in relatively wet areas.
Mortality became apparent in early May, the report said, peaking in the second half of May and early June.
One of the reports added that breeding commenced among bonxies as usual in May and June, but most attempts failed.
This is “mainly because one or both partners got infected and died”.
“The rapid spread of infections over Foula has probably been facilitated by the habit of Great Skuas to bathe and socialise at freshwater lochs and pools, sites where close conspecific interactions occur and where all major pathways of infection could play a role,” the report added.
But it suggests bonxies also had a poor breeding season in 2021, with an estimated three to four times as many dead adults as normal found in the colonies.
While no dead birds were tested for bird flu that year, the report says the assumption is that the virus was behind the increased deaths. Ringed birds found dead in the summer searches mainly originated from Foula itself.
Inspections of the more newly deceased birds found in Foula showed “highly characteristic behavioural aspects and postures” which led to researchers believing the birds suffered from avian influenza.
Avian influenza is primarily a disease of birds and the risk to the general public’s health is very low.
Figures reported by the BBC indicates that around 208 million birds have died across the world due to bird flu.
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