The farm birds in France's foie gras heartland are to be slaughtered to stem the spread of an outbreak of the highly pathogenic H5N8 virus.
Several culls have already taken place since December, dealing a blow to producers of foie gras — a controversial delicacy made from the livers of ducks and geese after force-feeding — in the run-up to the important Christmas season.
But until now only farms with infected birds were affected.
The latest cull targets free-range ducks raised for foie gras in the Gers, Landes, Hautes-Pyrenees and Pyrenees-Atlantiques areas, who risk contracting the virus from wild birds.
Duck farmers have accused the government of being slow to respond at the start of the outbreak, abetting its spread and increasing the number of birds now being led to the slaughter.
Since October, the strain has been detected in at least 13 European countries, according to the French government — including Germany, the Netherlands, Denmark, Poland, Hungary and Sweden.
The French government has promised that the farmers will be compensated, but some have complained of being underpaid following a similar outbreak in 2015 that set the industry back an estimated half a billion euros.
Most of the cases of infection have been in farms in the south-west but a handful have also been detected in wild ducks in the north.
In South Korea, over 10 million farm chickens and ducks have been slaughtered this winter as that country battles its worst bird flu outbreak since 2014.
In Japan, a million farm birds have been culled.