TOMORROW you'll probably be joining millions of Americans in a true Thanksgiving tradition: slathering giblet gravy over those dry, tasteless slices of turkey and tucking into the really good stuff -- the dressing and sweet potatoes, the cranberry relish and pumpkin pie.

I'm here to tell you there's hope.

The turkey you'll be eating could never exist in nature. After 50 years of overengineering, it has morphed into a bizarre, ungainly beast that can no longer run, fly or even lay eggs. And all in the name of progress: what it can do is supply copious quantities of white breast meat at the expense of the dark meat from the leg and thigh.

But there is a movement afoot -- among conservationists who understand that endangered animals can be saved if a commercial market is created for them -- to revive the breeds of turkey that once made people anticipate the Thanksgiving bird with pleasure because of its deep, rich flavor. The hitch, for the consumer, is that the farmers will raise only as many of these magnificent turkeys as they know they can sell, and they are not inexpensive. And because they are raised to order, orders must be placed near the beginning of the year.

While you're working your way through that big-breasted manufactured creation tomorrow, think of the treat in store for next year. Picture yourself, carving set in hand, beside a perfect Norman Rockwell turkey, with long legs and a taut golden brown breast. A moist, juicy turkey suffused with flavor, something you can sink your teeth into. People might actually ask for seconds.

The conservationist movement includes the American Livestock Breeds Conservancy, an organization that works to preserve rare breeds and genetic diversity in livestock and poultry; the Society for the Preservation of Poultry Antiquities; and a few hundred farmers around the country who raise small numbers of old breeds and have been trying to save them for years. And now Slow Food U.S.A., which is part of an international nonprofit education organization that promotes the relationship between environment and gastronomy, has joined the effort. Among its aims are saving foods that are part of America's heritage and endangered by agricultural standardization, like the Delaware Bay oyster, hand-parched wild rice from Minnesota and Wisconsin, and now, the American turkey. It has adopted four breeds near extinction -- the Narragansett, the Bourbon Red, the Jersey Buff and the Standard Bronze -- for its modern version of Noah's Ark. Next week it will announce the induction of the heritage turkeys, all of them native Americans, into its Ark U.S.A., with the hope that giving them a higher profile will increase demand.

''Ark products are food products that will be saved through consumption,'' said Peter Martins, the president of Slow Food U.S.A. ''Ark foods need to find work, and the best way is to be an everyday part of our diets. We want to increase demand of these products by increasing awareness.''

After years of selective breeding, only one breed of turkey, the aptly named Broadbreasted White, remains in large-scale production in the United States. For about 30 years, it has been the breeding stock owned by the three major companies, Hybrid Turkeys of Ontario, Canada; British United Turkeys of America in Lewisburg, W. Va.; and Nicholas Turkey Breeding Farms, Sonoma, Calif. A blowzy specimen with short stubby legs, its disproportionate supply of white meat has come at the expense of taste and texture. It's stupid to boot.

The joke about turkeys drowning in the rain may actually have some basis in fact. Glenn Drowns, secretary-treasurer of the Society for the Preservation of Poultry Antiquities, and owner of the Sand Hill Preservation Center in Calamus, Iowa, a preservation farm, is infuriated by the degradation of the turkey. ''The commercial guys say they have to keep the turkeys in buildings because they'd drown in the rain,'' he said. ''It makes my blood pressure boil. Next year I'm going to raise some of them to see if they are that far gone.''

Because most Americans aren't old enough to have eaten the old-fashioned turkey, they have no idea what they are missing. The rest of us just forgot over the years, lulled into thinking that new is improved. Tasting the four heritage turkeys against two Broadbreasted Whites, one of which was free range, reminded me why the Thanksgiving turkey was so eagerly looked forward to 50 years ago, and why, today, cooks have had to dream up dozens of ways of making it taste better.

The heritage turkeys I roasted were those chosen for inclusion in the Slow Food Ark because they were once in large-scale production and have delicious meat.

''They can compete with the commercial turkey, but the meat is more in the legs and thighs, because your muscles grow where you work them,'' Mr. Drowns said.

And unlike the industrialized turkey, which can barely walk, much less run, these turkeys forage all over the pasture. They can also fly, another activity the industrial turkey can no longer enjoy. Of the four heritage turkeys I roasted, the Bourbon Red was the most delicious, with more flavorful white meat than the other three and deeply flavored dark meat -- the essence of turkey.

But the differences among them were small, and a true test would require consumption of more than one of each turkey. All of them had richer, fuller flavor -- especially in the dark meat -- and were much juicier than the industrial birds, including the free-range version. The heritage birds also have texture, not as in tough but as in firm. The meat does not fall apart in your mouth, a characteristic of both industrial birds I roasted. The industrial turkeys were also very dry and had what might be called a ghost of turkey taste.

I also tried two Eastern wild turkeys from Quattro Farms, which sells them at the Union Square Greenmarket on Saturdays. They too have more flavor than the supermarket turkey, but they are much smaller -- 7 to 12 pounds -- than the four heritage turkeys, which weighed 14 to 18 pounds. Mr. Drowns says it's easy to tell the heritage and the industrial turkeys apart. ''I could pick out the industrial bird from the one raised naturally even blindfolded,'' he said, ''even with the best chef in the world cooking.'' The difference in taste is not just because of genetics but also because of their varied diet and their ability to graze, hunting and pecking for the grubs and bugs and grasses that make them taste good. Their firmness is due to their exercise. They also appear to have a nutritional advantage over industrial birds: because they eat more grass they have higher levels of the good omega-3 fatty acids, which may protect the heart and bring down levels of unhealthful triglycerides.

The common ancestor for all heritage breeds is the wild turkey, native to these shores. Wild turkeys went from Central America to Europe with the first explorers. Then they were imported to North America by English settlers as the black Spanish turkey, which was bred with the wild North American turkey. The Standard Bronze was the result and the other breeds followed: the Narragansett from Narragansett Bay in Rhode Island; the Bourbon from Bourbon County, Ky., and the Jersey Buff from New Jersey.

Fifty years ago, when Americans were still eating turkeys raised nearby, there were millions of those birds. Paula Johnson, who raises heritage turkeys in Las Cruces, N.M., recently surveyed the heritage turkey population. She said there are only about 3,800 of them left, raised mostly for show. Only about 23 farms have flocks with more than 100 turkeys. At the moment, only the owners and a few of their lucky neighbors can enjoy them for holiday dinner.

The disappearance of the endangered breeds came to public attention with the release of a census in 1998, when the American Livestock Breeds Conservancy began an intensive campaign warning of the imminent extinction of those turkeys. The conservancy lists the Buff, Narragansett and Bronze as critical, which means there are fewer than 500 breeding birds in North America. Bourbon Reds are classified as rare, with fewer than 1,000 breeding birds.

With only one breed of turkey available in significant quantities, it is possible that 50 years from now there will be no turkeys at all for Thanksgiving dinner. ''The gene pool is so narrow in the industrial turkey that they are beginning to notice heart problems, leg failure, suppressed immune systems,'' Mr. Drowns said. ''If you don't have a gene pool in the natural mating turkeys, you are talking about coming up with something else to eat for Thanksgiving 40 or 50 years from now. The industrial turkeys could be wiped out by a virus, by bacteria or just plain stress.''

Commercial turkeys can no longer breed on their own; they are artificially inseminated. They don't lay eggs; their large breasts make it impossible for them to mount. Pamela Marshall, who breeds heritage chickens and turkeys in Amenia, N.Y., paints a vivid picture. ''It's like having two footballs mate,'' she said. The American Livestock Breeds Conservancy says that of the 10 species of domestic farm animals that are the focus of their work, ''none is more genetically eroded than the turkey.''

Donald Bixby, executive director of the conservancy said: ''With industrial turkeys, everyone is breeding for a narrow range of production characteristics. So, as a result, they are losing survival characteristics. That's why they are having a hard time breeding, why their biological fitness is declining, why there is infertility, bone and joint problems, ruptured aortas, hypertension.''

In other words, the modern day turkey, in addition to being dry and tasteless, is a physical wreck. These turkeys are also bred to be ready for slaughter when they are three to three and a half months old, which explains why they are so dry.

''When you shorten the life of the bird, it never matures and never puts on the layer of fat, and that's why these commercial birds taste real dry and why they are injected with liquid,'' said Frank Reese, who raises Bourbon Reds, Bronzes and Narragansetts on his ranch in Lindsborg, Kan. Like others raising rare breeds, Mr. Reese sells his birds when they are five or six months old and have acquired some fat.

The modern turkey has also been bred to look perfect, Ms. Marshall said. ''In the 1950's and 60's we developed into an antiseptic nation and wanted perfection -- the perfect white breast,'' she said. ''As people have become more aware of what goes into food, how it is produced, they have become more tolerant of imperfections like dark pinfeathers in dark birds. Now people are more concerned with the quality of the food.''

For many, that has meant years of taking extreme measures to add flavor and moisture to the turkey.

Imagine a day when it would no longer be necessary to spend hours soaking the bird in brine. Deep-frying turkeys could be saved for warm weather, when the task can be safely accomplished outside, reducing the odds of burning down the house. The chances of pneumonia would decrease, as outdoor grilling in a freezing rain would no longer be necessary. Poisoning the dinner guests would be significantly reduced, because the technique of cooking the turkey at very low temperature overnight could be discarded. So could the one that calls for cooking at very high temperature and setting off the smoke detector.

Talk about being thankful.

Correction: December 5, 2001, Wednesday An article on Nov. 21 about a campaign to preserve rare breeds of domesticated turkey referred incorrectly to the Broadbreasted White, today's main commercial variety, which suffers a number of side effects from selective breeding. While it must be inseminated artificially, it can in fact lay eggs.