There’s no need to send another World Health Organization mission to China. The last time we did that (to unearth the source of Covid-19) the Chinese authorities delayed and censored the inquiry. Besides, this time we know the origin of bird flu: the strain currently running amok on four continents originated in intensive poultry farms in southern China.

15.74 billion poultry birds were slaughtered in China in 2021

Bird flu is a contagious disease caused by a virus loosely related to human influenza. As with other viruses, it evolves rapidly into different strains. Most cause little or no harm in infected wild birds, but the latest strain is far more deadly.

Dried shark fins for sale in a Taipei market. © Craig Ferguson/LightRocket/Getty

In summer 2022, we experienced the worst outbreak of avian flu ever witnessed in the UK, with countless thousands of birds dropping dead around the country. Overall, more than 60 species have tested positive (including six species of raptor). But northern gannets and great skuas are the worst hit and many more of our internationally important (and already beleaguered) seabird populations have suffered particularly badly. Similar catastrophic stories are being reported across the globe.

A great skua that succumbed to avian flu in Shetland
A great skua that succumbed to avian flu in Shetland. © Ashley Cooper/Getty

Meanwhile, as many as hundreds of millions of poultry birds have been infected in Europe, North America, Africa and Asia (nearly 50 million chickens died in 2022 in the US alone, due to infections or culls). It’s just a matter of time before it reaches Central and South America and Australia – and, heaven forbid, Antarctica.

the most significant cause of the global spread has been intensive factory farming

But it’s the origin of Highly Pathogenic Avian Influenza H5N1, to give it its proper name, that really worries me. There is speculation that wildfowl and other migratory wild birds are the main cause of the virus spreading; indeed, they can spread it over long distances and between neighbouring countries. (Please don’t tell those responsible for the badger cull – or they’ll want to make a scapegoat of our wild birds and cull them.)

The truth is that the most significant cause of the global spread has been intensive factory farming combined with the unrestricted movement of poultry and poultry products.

In China, factory farming of chickens, turkeys, ducks and geese is growing vigorously. The scale of the industry is already staggering – 15.74 billion poultry birds were slaughtered there in 2021 – and several new gargantuan factory farms and slaughter complexes (each housing 100 million birds) are in production.

Such large-scale factory farms inevitably provide the perfect environment for a mutating virus – closed to the outside world, dimly lit (UV light can harm viruses), crowded, stressful and unsanitary. It’s a perfect storm of our own making.

But China is not alone. Driven in part by supermarket pressure to keep prices low, and consumer demand for cheap meat, the march of mega-farms continues apace in the UK. We pretend to know better, yet we have more than 1,500 industrial-sized poultry farms – seven of them housing more than 1 million birds. No fewer than 1.14 billion poultry birds were slaughtered here in 2021.

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What to do? In the short term, a shocking 48 million poultry birds were culled in the EU in the first 9 months of 2022 (plus 3.2 million in the UK). The culling continues. Meanwhile, an Avian Influenza Prevention Zone was declared across England, Scotland and Wales in mid-October, requiring strict biosecurity measures to mitigate the risk of the disease spreading. In the longer term, an effective vaccine for poultry could help to stem the spread.


But most of all we need to rid the world of factory farms. How many reasons do we need? The ethical and environmental grounds were already compelling enough – and now we have the proven risk of a pandemic.


Mark CarwardineZoologist, activist, author and presenter