"Normally, we'd receive between 200 and 250 packages a day from our (foie gras) suppliers. At the moment it's only about 120 a week," says Bruno Courillon, head of poultry firm Eurovolailles.

The foie gras industry in France's southwest has suffered a bird flu epidemic for the second year in a row. The culling of millions of ducks meant firms had to suspend production for up to 10 months.

Foie gras output this year is expected to be 44 percent below 2015's level, producers' group Cifog estimates.

Snails, for which the holiday season accounts for more than half of annual sales in France, are also likely to be more expensive because of their butter-rich stuffing.

Butter prices have doubled this year due to tighter international supply, and tensions between suppliers and retailers over who should bear the cost contributed to shortages in French stores this autumn.