- By Georgina Rannard
- Science journalist, BBC News
A powerful bird known as the sea pirate has suffered a dramatic decline due to bird flu, according to the RSPB.
Great Skuas fly over UK shores to steal food from other birds, but their numbers in 2023 were down 76%, the charity said in a report.
Populations of Gannets and Roseate Terns were also significantly reduced after avian flu killed thousands of wild birds in 2021-22.
The numbers of all three species were increasing before the epidemic.
The H5N1 strain of bird flu spread to wild birds during the summer of 2021, causing the deaths of thousands of the creatures.
The results clearly show that avian influenza is “one of the greatest immediate threats to the conservation of many seabirds”, says the RSBP.
“This is a wake-up call to the seriousness of avian flu and adds to the multiple other threats these species face,” says RSPB avian flu policy assistant Jean Duggan.
The RSPB studied 13 bird species in May-July 2023 and concluded that avian flu had caused the decline of Great Skuas, Gannets and Roseate Terns, and was most likely to blame of a reduction in Sandwich Terns and Common Terns.
Gannet populations are down by 25%, Roseate Terns by 21%, Sandwich Terns by 35% and Common Terns by 42% compared to a major bird population census carried out in 2015- 2021.
Almost the entire UK population of Great Skuas lives in Scotland. As of 2022, at least 2,591 Great Skuas have died, including 1,400 from a single colony on the island of Foula, Shetland.
The total number in the UK fell from 9,088 to 2,160.
Ms Duggan stressed that Britain plays a central role in protecting the bird worldwide, as many birds breed in Britain.
“It is encouraging to realize that if we take the right steps in the UK, it will actually benefit global populations to a very significant extent,” she says.
Gannets have also been hit hard in 2022, with 11,175 deaths in Scotland and around 5,000 deaths in Grassholm in Wales.
In 2023, the total number of people counted in the UK fell by 25%, from 227,129 to 171,048.
Avian flu has become less acute in the UK in recent months, but it has caused mass die-offs of birds in other parts of the world.
In January, it was first detected in elephants and fur seals in Antarctica.
“Although the virus is still present around the world, British birds are still at risk and the virus will continue to mutate. We need to view it as a long-term threat,” Ms Duggan says.
Climate change, fishing-related mortality, the effects of offshore wind power development and reduced food availability are other threats facing UK seabirds, according to the RSBP.
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