Bird flu: what is it, which populations are affected and what are the long-term impacts?
A highly infective strain of bird flu has killed thousands of seabirds and waterbirds across the UK, devastating avian colonies at the height of the breeding season. What are the long-term impacts and can any lessons be learnt for welfare within the food industry?
There is a highly pathogenic strain of bird flu currently rife across the UK, decimating populations of seabirds and waterbirds.
Here, we bring you everything you need to know about this current strain of bird flu, the bird populations affected and what the plans are to minimise further outbreaks.
What is bird flu?
The latest wave of avian flu descends from the H5N1 strain of avian influenza that originally arrived in the UK in 2005/06, most likely from dense poultry and geese farms in China and south-east Asia.
"Most of the time this has behaved like a normal, natural avian flu, coming and going, bad some years then dropping to a low level," says Martin Fowlie of the RSPB.
"But it’s fair to say this is the worst ever outbreak in the UK. We have been in uncharted territory with the disease this year and its effects on wild birds. It has mutated into a really nasty strain."
Where did this current strain of bird flu come from?
The latest version emerged in the summer of 2021, when sick and dead great skuas were found in Shetland, Orkney, St Kilda and the Flannan Isles. Other seabirds and waterbirds were affected over the 2021/2022 winter but this spring it surged again, hitting colonies as they returned from the open sea to breed.
How do birds become infected with bird flu?
Birds can be infected with the virus through contact with infected saliva, nasal secretions or faeces. Wild birds including waterfowl are often more resistant to avian influenza than domestic birds, and can carry and transmit the virus without showing evidence of disease. Movements of poultry around and between countries, is another known vector.
How many birds have died from bird flu?
The true number may not be known as many birds die at sea or are washed away. There is no cure or treatment and almost all infected birds die. "We are looking at hundreds of thousands of birds," says Fowlie.
Britain's seabird populations are of global significance, with the UK holding 56% of the worlds northern gannet population and Scotland holding 46% of the world’s northern gannets and 60% of the world’s great skuas. Both these species are amber listed in Birds of Conservation.
As of early October, 537 positive cases of the strain had been identified in Scotland, among 28 species over 142 locations, though the true number will be far higher.
Bird flu survives after it has killed its host and there is concern that it could spread widely in white-tailed and golden eagles when they scavenge or kill dead or infected birds.
Which species have been affected by bird flu?
- Great skuas: Some colonies have lost up to 80% of their populations . The National Trust for Scotland (NTS), which manages the Unesco World Heritage of St Kilda, which lies 40 miles west of Harris and Uist, said a significant proportion of the islands' great skuas. Also known as bonxies, dead birds have been found on Papa Westray, Shetland and elsewhere.
- Guillemots have also been hit. ‘We have seen chicks washed up as well. They jump off the cliffs with their dads when they leave the nest. We don’t know if they have got the disease or they have starved when their dads die," says Fowlie.
- The key roseate tern population on Coquet Island in Northumbria has also been devastated.
- Black-headed gulls have been found dead from the disease in Suffolk.
- Ornithologists estimate 3,000-4,000 barnacle geese died over the 2021/22 winter around the Solway firth, a third of the regional barnacle geese population.
- More than 100 gannets have died on St Kilda. At Bass Rock in the Firth of Forth, the world’s largest gannetry has also been hit with more than 150 dead birds discovered along the coastline. Others have been found dead at Noup Head in Westray.
- The impact on the European continent and further afield has been similar with at least 400,000 wild birds estimated to have died in 2,600 outbreaks. Among poultry, 3,000 reported outbreaks have led to 77 million birds being culled.
Curiously so far puffins, kittiwakes and fulmars have been relatively unscathed, even when they have bred in multi-species colonies where other species have been hammered. The RSPB is keen to establish if this is down to chance or something more significant.
Defra and the UKHSA says the risk of avian flu in common garden bird species such as finches, sparrows, tits, warblers, robins, wrens, swallows as well as pigeons is very low.
What happens next?
NatureScot, the Scottish government environmental agency, said the virus is likely to remain in circulation "for some time".
"The problem," says Fowlie, "is that this deadly strain of avian flu has hit extremely vulnerable populations that are already under great pressure. Bird flu is just more thing our seabirds have to deal with.
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Our seabirds are already under massive pressure from human impacts including climate change, lack of prey fish, deaths through entanglement in fishing gear and development pressure."
In the absence of effective monitoring or measures, the RSPB and others are crossing their fingers that avian flu recedes over the winter. "The concern is if it comes back again to already depleted populations," says Fowlie. "We are hearing talk of potential extinction for some species such as the great skua".
Is it only wild birds who are affected?
No. Several reports of H5N1 have been identified over the summer at poultry farms across the UK. Protection, exclusion and surveillance zones were set up in affected areas. One consequence of this was a requirement to house poultry, leading to eggs no longer being classified as free range.
Do imported birds and poultry products play a part in the disease?
Not only is avian flu likely to have originated in Asian poultry farms and arrived via processed and air-freighted meat but current practices may compound the problem. Ornithologists have expressed disquiet at the widespread import of game birds for the shooting industry from France where the major breeding sites for pheasants and partridges in the Vendée and Loire Atlantique has been affected by avian flu. Restrictions were in place over the summer and the release of game birds in restricted zones in the UK was prohibited.
What can be done to prevent or minimise future outbreaks?
Nothing can be done to save individual birds infected. But the RSPB believes that to deal with future HPAI outbreaks in wild birds, improved surveillance, testing and carcass collecting is essential; and that an effective plan should be put in place for biosecurity measures and to minimise disturbance.
"Scotland and Wales have put some measures in place but in England it is glaringly absent," says Fowlie. "When bird flu first arrived there was a task force, a collaboration of virologists, vets, ecologists – that was important and so useful. For whatever reason, that has not happened this time.
"We need to be more joined up in how we deal with our marine environment. We need to tackle invasive species such as rats and mice in colonies, reinforce and effectively police our marine protected areas, we need to be cleverer about where we put offshore wind farms. Monitoring of trends and populations is needed – funding for data has dried up."
What to do if you see a dead bird
The risk of contracting the disease from a wild bird is very low but you are advised not to touch any sick or dead birds, their droppings, or any water nearby as the virus survives long after it has killed its host. Should you find any dead swans, ducks, geese, gulls, seabirds, birds of prey or five or more of any other species in one place report them to Defra on 03459 335577 or in Northern Ireland to DAERA on 0300 200 7840.
Top image: Great skua/Credit: Getty Images
Mark Rowe is an environmental and wildlife journalist and author who has written for Countryfile magazine since its first issue and writes our monthly Behind the Headlines feature. He also writes for national newspapers and magazines including Geographical and the Independent. He is the author of three guidebooks for Bradt Guides - on the Outer Hebrides, Orkney and the Isle of Wight. He is also the author of the popular online guide Slow Wight. He still believes a paper map is superior to online versions & can often be spotted chasing an OS map across a windswept hilltop.
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