Kiki sniffs the air, half rises on her hind legs, then bolts into a stand of oak trees, dragging her leash and the retired postman at the end of it with her.
''Allez! Allez cherchez!,'' cries Raymond Boisset, as he lopes to keep up with his truffle-hunting pig.
The pig pauses over a patch of bare ground under a tree. Sniffs turn to snorts. Then, tail twitching, she plunges her snout into the damp earth.
Using her snout as a shovel, she tosses up clumps of soil, pebbles, bits of twig high into the air. Mr. Boisset leans over the deepening hole, just out of the line of flying debris, watching closely.
With a sharp tug on the leash, he yanks the eager pig away from her prize. A quick handful of cheese chunks distracts her, as he nudges a fragrant black truffle out of the earth.
''I have to jerk the leash just before she takes a bite,'' he says, brushing soil from his $400-a-pound treasure. ''Otherwise, that truffle would be gone.''
France's winter truffle-hunting season has just ended. While it brought higher prices than ever, long-term prospects for the region's ''black gold,'' prized for the distinctive look and flavor it brings to food, are not promising. French truffles -- and those who care for the grounds that support them -- are disappearing.
At the turn of the century, French peasants unearthed 800 tons of truffles. Harvests took a sharp drop after World War I, a war that killed about 1 million French peasants. After World War II, many rural workers left the countryside for jobs in the cities. Those who stayed adopted more mechanized forms of agriculture that broke up the soil, and with it, the life cycle of truffles. Harvests plunged to 80 tons in 1960, 60 tons in 1970, 35 tons in 1980, and to an estimated 15 tons in this year's harvest, the lowest ever.
''The problem with truffles is a human problem,'' says Pierre-Jean Pebeyre, whose great-grandfather started buying and selling truffles in 1897. ''There's no one left to grow them.'' The Cahors-based Pebeyre Ltd. now handles about one-third of the truffles sold in France, and supplies many of the world's leading restaurants.
Truffle markets took hold in rural France in the late 19th century, after phylloxera decimated many vineyards. The hillsides around the Cahors, once covered with vineyards, were replanted with oak trees to create truffle grounds. Now these stands of oak are past maturity and overgrown. ''If there are fewer truffles today, it's because we don't consider them as a vegetable, but as a dream, as folklore,'' Mr. Pebeyre says. ''There are few growing things that are black, and these grow entirely underground. People think of them as mysterious.''
''The culture of truffles is difficult,'' he adds. ''You need to plant trees, then wait 15 years before they begin to produce. You'll have about 30 years of production, then decline. You need to spread fertilizer, maintain the trees, and supply water when it gets too dry. But people think, 'Why carry water to a mysterious product?'''
Black truffles are often described as a mushroom, but are actually the offshoot of a fungus that grows in symbiosis with certain trees, especially oaks. The entire life cycle of the truffle is underground, and little is known about it.
INRA, France's National Institute for Agronomy Research, is providing subsidies for growing truffles and experimenting with methods of culture in an effort to understand the relationship between trees and truffles. But Pebeyre insists that future of the industry in France depends on a clear understanding of the life cycle of the truffle.
''For the last 15 years, my father and I were aware that the industry was headed for an impasse. You can't watch production drop to the extent it has without recognizing that you need to find a way to commercially grow truffles. To do that, you need to understand how they reproduce,'' he says.
But researchers are far from creating test-tube truffles. ''The first doctorates on the biology of truffles were given in the 1980s,'' says Michel Kulifaj, who was part of the team at the University of Toulouse to take up this research. His current work on the life cycle of truffles is funded by Pebeyre labs.
''The problem is that you can't observe the life cycle of a truffle,'' Mr. Kulifaj says. ''It's all underground. You can have hypotheses, but it takes a year [the growing season of a truffle] to confirm them. I've tried for years to understand why truffles reproduce, and still have no idea.''
IN the meantime, truffle hunters are looking for new ways to find the truffles that remain. Dogs and -- implausibly -- flies could provide a more cost-effective approach to locating truffles. Certain fly species lay eggs over truffles, and hover above ground over their eggs. By lying on the ground and watching for these insects, truffle hunters can do without the pig.
But Kiki's job security is in no immediate danger. The young terrier that Boisset bought to replace her has demonstrated no interest in sniffing, eating, or finding truffles. He turned up his nose at the one offered from Kiki's afternoon's labor, and went for the remaining cheese chunks.
''He's useless,'' sighs Boisset. ''But I like him.''