Today, Mr. Ducasse and his confreres say their main objective is to revive a culinary tradition that dates to Roman times, when emperors sought out the ortolan’s intoxicating taste, and to pass the savoir-faire to a new generation of cooks. “We want to be able to do this so as not to lose all the beautiful things that make up the history and the DNA of French cooking,” Mr. Guérard said.

The European Union banned the hunting of ortolans and declared them a protected species in 1979 amid concerns about their survival and an outcry from environmentalists. But France waited two decades to codify the measure.

Still, many people in France continue to capture and eat the birds. Families in Landes would traditionally savor them once a year, “like a bonbon” at the end of a big lunch, eating them in total silence with a glass of Sauternes and the shades drawn, said Mr. Dutournier, a native of Landes and the head chef at Carré des Feuillants in Paris, which has two Michelin stars.

Wearing the white napkin allows diners to savor the aromas and enjoy some privacy while devouring the bird — or, critics say, hide their indulgence from the eyes of God.

Eating ortolan is also a surreptitious pleasure beyond France: The author and chef Anthony Bourdain, in his 2010 book, “Medium Raw,” described a secret, late-night meeting of French chefs in a New York restaurant to eat ortolans. “It’s sort of a hot rush of fat, guts, bones, blood and meat, and it’s really delicious,” he told Stephen Colbert in an interview.

Such extravagance can involve an uncomfortable trade-off. Poachers lure the ortolan into ground traps during its migratory flight from Northern Europe to Africa. Mr. Dubourg, the activist, said that because the birds are prized for their fat, they are kept in darkness for 21 days and are sometimes blinded, prompting them to gorge on millet and grapes. Once the ortolan’s fat has tripled in volume, the bird is drowned with Armagnac, plucked, roasted and served hot in its entirety. “Good cuisine cannot be used as an excuse for the condition these animals are kept in,” Mr. Dubourg said.