French authorities have started slaughtering ducks in the main foie gras-producing region to try to contain a dangerous form of bird flu.

Operations to destroy birds got underway Thursday in three departments of southwestern France where an outbreak of the H5N8 virus hasn’t stabilized.

The virus doesn’t transmit via food and is harmless to humans.

The cull is expected to last until Jan. 20 and could potentially affect as much as 1 million ducks.

Since December last year, 89 outbreaks of bird flu have been reported in France, most of them in southwestern France.

According to the Agriculture Ministry, the quick spread of the virus justified the cull, which will be accompanied by compensation measures for farmers.