What’s killing our birds?

If you are a bird, any kind of bird, the current pandemic of avian influenza rampaging through your kind is far more terrifying than anything the hairless apes on the ground below experienced in 2020 and 2021. Britain’s seabirds – guillemots, gannets, gulls, kittiwakes and skuas – have been hardest hit because they breed in dense colonies, facilitating infection. The death toll this summer among 2,600 sandwich tern chicks on Coquet island, off the Northumberland coast, approached 100 per cent.

The worst may be only just beginning for the many thousands of geese, ducks and waders. They scatter across the Arctic tundra in summer and gather in dense flocks on estuaries and salt marshes around our shores in winter. Last winter barnacle geese died in their thousands on the Solway Firth – and many buzzards and crows perished from eating their corpses.

This vicious version of bird flu reached Europe from Asia last year, spread to North America this summer and will be carried to the Pacific coast and South America by migrating birds this winter. From pelicans to plovers, no species seems immune: the disease has already been diagnosed in 108 wild bird species in America.

What has changed to cause this unprecedented pandemic? The strains that are killing birds are collectively called H5Nx 2.3.4.4b. Piecing together the history is not easy, but it appears that the immediate ancestor H5N1 originated in poultry farms in China in 1996. Before that, episodic eruptions of avian influenza in domestic fowl were common, and the virus has always been endemic in wild birds. Indeed, it’s likely that human flu came originally from birds, perhaps via pigs.

The 1996 outbreak led to 18 human cases in Hong Kong the following year and six deaths, precipitating a series of scares about the threat to human beings and new precautions in the poultry industry.