Foie gras is central to French Christmas. But this year, the specialty made from the liver of geese and ducks, is in short supply due to a large number of birds that were killed after they contracted bird flu in France last year. Now, prices are high, and between the costs and the repeated calls to boycott foie gras because of the treatment of animals involved, poultry farms are facing a hard time. Gerry Hadden follows the story from farm to market to restaurant in Southern France and Barcelona, Spain.