The Scale is hard to grasp: avian flu wreaks devastation on seabirds

Press/Media: Expert Comment

Description

A quarter of Europe’s breeding seabirds spend spring in the UK, turning our coastline into a giant maternity unit. These noisy outcrops usually stink of bird poo. However, this year has been different. “Instead of the smell of guano, it’s the smell of death,” says Gwen Potter, a National Trust countryside manager working on the Farne Islands, off the coast of Northumberland. “It’s completely horrendous.”

This annual congregation of life has turned into a super-spreader event, as a highly pathogenic avian influenza, H5N1 – also known as bird flu – sweeps through populations of breeding birds, causing devastating losses. More than 300 outbreaks have been reported in UK seabird colonies, and dozens of coastal sites have closed to the public.

 

The Farne Islands are home to 200,000 seabirds, including Arctic terns, Atlantic puffins, guillemots, kittiwakes and razorbills. Potter is one of many conservationists swapping binoculars for a hazmat suit, picking up the bodies of birds she has spent her career trying to protect. Birds will sit on the ground, unable to move, twisting into unnatural positions, before dying. It is happening with chicks, too, still gently trying to flap as they die. “It sweeps through, takes everything in its path. It doesn’t seem to spare anything, really … We’ve collected thousands of dead birds, and that’s the tip of the iceberg. It’s just the scale of it which is hard to grasp,” she says.

Early observations suggest that how closely the birds nest is a key factor in how quickly the virus is transmitted. Guillemots nest quite densely, and kittiwakes are often next to them, which makes them vulnerable, although there is more space between them. Terns also nest densely and already 25% of the 350 sandwich terns on the Farne Islands are thought to have died, according to Potter. Some seabird chicks jump into the sea prematurely if their parents have died, while others starve in the nest.

Most seabirds will fly away in the coming weeks once their chicks are raised, but the true impact on populations will not be known for a few years, with concerns that some may never recover. “I don’t want to contemplate that because it will make me cry,” says Potter

In terms of how the virus will spread, Prof Paul Digard, the chair of virology at the Roslin Institute, University of Edinburgh, says it is impossible to generalise from one species to another, so he doesn’t believe it will kill 100% of those it infects, partly because of intrinsic genetic differences, and partly because of factors such as stress, age and other traits in specific populations.

He says H5N1 is causing a huge amount of damage because it is spreading among populations that have not had the virus before, but that this will change in the future because some will survive. “My guess is that things will calm down over time as populations gain immunity to this circulating strain of virus. I would hope not to see the same levels of mortality in the coming years, but that’s something of a guess,” he says.

A dead eider duck lies on pebbles on the shore of Loch Flee

The avian flu outbreak has now spread to many species, including this eider in Loch Fleet National Nature Reserve. Photograph: Peter Stronach

The main factors contributing to its spread are international trade, the farming and sale of birds, and the migration of wild birds, according to the World Organisation for Animal Health. Birds that have no symptoms could be super-spreaders because they can still fly long distances.

However, Bell says she has never heard of an asymptomatic bird with the virus and therefore doesn’t think wild birds would be able to spread it over long distances. She believes the international poultry trade is the main driver of the virus and says stopping imports of chicks and birds for the trade would be an important step in reducing the risk of future outbreaks. “Originally, it was poultry to wild birds; it was not wild birds which were spreading it. It was frustrating to see wild birds being blamed … We’ve got to get out of our heads that the wild birds are the bad guys here,” she says.

The public should keep their distance from any carcasses and report them to the government helpline. At the moment it does not appear to be infecting humans, but previous strains of the virus have. “If you see a sick bird, leave it be, I’m afraid,” says Digard. “Don’t take it to an animal shelter. You are potentially signing a death warrant for all the other birds in that shelter.”

The most important thing would be better surveillance of the situation, says Potter, who believes there needs to be a government-led plan for all four UK countries, with guidance for effective carcass collection and testing, and better biosecurity on poultry farms. Seabirds have already been hit by a range of threats, including habitat loss, overfishing and climate change; their populations have halved since the 1980s. Reducing these other pressures would make them more resilient to bird flu.

A spokesperson for the Department for Environment, Food and Rural Affairs said: “There are limited effective actions that can be taken to protect wild birds, as opposed to captive bird flocks. Due to the migratory habits of wild birds, it will only be with breeding season monitoring next year that the full impact will become apparent. However, the Animal and Plant Health Agency (APHA) carries out year-round avian influenza surveillance of dead wild birds, and clear public guidance has been issued not to handle their carcasses.”

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Period20 Jul 2022

Media contributions

1

Media contributions

  • TitleThe scale is hard to grasp’: avian flu wreaks devastation on seabirds
    Degree of recognitionInternational
    Media name/outletThe Guardian
    Media typePrint
    Country/TerritoryUnited Kingdom
    Date20/07/22
    DescriptionDozens of coastal sites in the UK closed to the public as H5N1 continues to sweep through wild bird populations across the world
    PersonsPaul Digard