The great skua is a noisy bird. It calls with a harsh “hah-hah”, a loud warning for those who venture too close. This fearless bird — known as the “pirate of the sea” — will often dive-bomb any human judged to be on its turf.
But its breeding grounds on the islands of St Kilda, Shetland and Orkney have been much quieter in recent months. Bird flu has ravaged its populations, with 85 per cent of some colonies thought to have been killed in the outbreaks.
James Pearce-Higgins, director of science at the British Trust for Ornithology, fears this charismatic species is facing extinction. “The UK has 60 per cent of the world population of great skuas,” he said. “If we’ve lost 10 per cent of that — and it could well be a much higher figure — it will take a long time for the population to recover. These are long-lived and slow-reproducing species. But if we have another bad season next year, then there is a significantly heightened risk of global extinction.”
Bird flu, or avian influenza, is the pandemic that you may not have heard of. The UK and Europe — in fact the whole of the northern hemisphere — is facing the worst outbreak it has seen. Some 3.5 million chickens, ducks and turkeys have been culled on British farms, and 48 million across Europe, in the past year.
This month, in parts of England, poultry was banned from being kept outside for the second time in a year, meaning free-range eggs have to be relabelled as “barn-laid”.
Advertisement
The impact on wild birds is expected to be greater still. Seabirds such as gannets, guillemots, kittiwakes and puffins have been found dead around the British coast, from the Hebrides in the north to the Isles of Scilly in the south. The National Trust estimates up to 50,000 birds could die on the Farne Islands off Northumberland.
Even some of our rarest birds of prey, such as hen harriers and white-tailed eagles, have been affected. “It’s not significant enough yet among these species to have population-level consequences, but it’s something we’re having to watch,” said Pearce-Higgins.
This conservation crisis is being caused by H5N1 — a form of avian influenza that first emerged in southern China in 1996, and appeared in humans in Hong Kong in 1997, when it crossed over from poultry in an outbreak that affected 18 people, killing six of them. That incident, with its high mortality rate, terrified health authorities around the world, and is one of the reasons international pandemic planning — until the appearance of Covid-19 — focused almost exclusively on flu.
Since then, H5N1 has circulated the world every year, occasionally jumping to humans. The World Health Organisation earlier this year reported there had been 863 cases since 2003, with 455 deaths. In January Alan Gosling, 79, of Devon, contracted H5N1 from his Muscovy ducks, but later recovered. Last month, a worker at a Spanish poultry farm in Guadalajara contracted the virus.
Paul Digard, professor of virology at the Roslin Institute near Edinburgh, said the danger to humans had become smaller since H5N1 emerged 25 years ago. “It seems to have become less infectious for people over the years,” he said. “That’s not to take it trivially. We have to keep an eye on it, because it could change back the other way. But right now, I don’t think this is a major danger to people.”
Advertisement
For wild birds, however, the virus has become more dangerous. In previous years waterbirds — particularly ducks, geese and wading birds — have been the main source of avian flu, bringing the virus with them as they flew into Britain each autumn from Europe and the Arctic. When they flew back in the spring, they took the virus with them.
This year, the pattern changed. Christine Middlemiss, the UK chief veterinary officer, said: “For the first time ever, we’ve seen the virus oversummer with us in our native wild bird population.”
When it infected the first seabirds, which live in huge, dense colonies on our coastal cliffs and islands, it quickly spread. Why did this happen? “Almost certainly, these changes have to be because the virus has changed,” said Digard. That precise change has not yet been identified — avian influenza has not received the same sequencing resources as Covid-19 — but scientists are working on it.
Like Covid-19, however, it raises the question of what will happen in future years. “Is the virus causing so much devastation because it’s in a totally new population with no immunity?” said Digard. “If so, then hopefully the survivors from this last summer will have more protection next summer, and things won’t be so bad. Now that it’s managed to stick around over the summer, it does make us wonder, will this virus become endemic in the future?” As with Covid-19, the hope is that bird populations will reach herd (or rather, flock) immunity.
What will it mean for our food supplies? With 3.5 million poultry culled, will we face a shortage of Christmas turkeys? Middlemiss, the chief vet, offered reassurance. “We produce nearly one billion birds a year for eating as meat. And for Christmas, we produce approximately nine to ten million turkeys. While it’s devastating for those particular companies affected, for the overall food supply, at the moment, we don’t believe it’s going to have a significant impact.”
