ALL OVER the Hamptons, the Mercedes and the Rolls-Royces are clogging the highways heading west toward Manhattan. Ferrying the well-known (and those who wish they knew them) back to the city, they are leaving the village parking spaces to the Renegade jeeps, mud-splattered pickups, and American compacts. On the day after Labor Day the only thing flocking into the towns of the South Fork of Long Island are the Canadian geese, punctuating the quiet with their abrasive honks as they fly overhead toward the ponds north of the villages.

On the streets talk of Prince racquets and parties is replaced by talk of high school football triumphs and the quantity of bluefish caught that day. At the Village Cheese Shop on Southampton's Main Street, which this year had to install a number system to keep the Ellesse-clad clientele from near fisticuffs while ordering pasta salads and pate''s, the customers are once again local merchants and shopgirls picking up a buttered hard roll and coffee to go. The number system has been temporarily abandoned at "95."

A few doors down is Herricks Hardware, a white clapboard village institution in business for more than half a century, where they cling to the old ways and haven't yet installed numbers. Here you can still find that hard-to-match shade of paint, mixed to order, replace the oddest combination of screw and bolt, and buy unenameled cast-iron pots. The chaos associated with the summer crowd has given way to the more leisurely shoptalk between the clerks and the regular patrons -- carpenters, handymen, and year-round homeowners who do their own repairing without resorting to nameless panic.

A mile from the square-block shopping area, down tree-shaded streets and past grand estates hidden by thick hedges, lie the justly famous beaches. It is here in the summer that bodies as sleek as the cars they drive turn brown without ever burning, where jogging along the water's edge is a fashionable pastime, and where it is nearly impossible to find a parking space.

After Labor Day, the beaches belong once more to the lone hiker, the solitary surfcaster, waiting patiently for the elusive striped bass, and the young surfer riding the fall Atlantic. The parking lots, particularly those with an unobstructed view of the ocean, are now used almost exclusively by pick-up trucks. The drivers, never having to leave their seats, watch the sea while lunching on a fast-food burger.

Fall has arrived in the Hamptons and the sigh of relief that accompanies the exodus of the summer people is almost audible. Strangely enough, it comes from everyone left behind. You can hear it from the shopkeepers and service people who benefit most from the summer crowd, from the year-rounders who don't want any part of them, and pride themselves on strict avoidance of the villages and the main highways in season, and from people like myself who regularly summer and weekend and with the onset of fall yearn to become a year-rounder if only for three glorious months.

For the local residents, the fall is a time of reclamation, of "having the place to ourselves again," as one friend puts it, and there is general agreement that it is the most spectacular season of the year. You can almost see the place turning back to the South Fork -- its regional name -- and the people reclaiming their natural heritage. Even the uniforms change. Where only weeks ago there were tennis racquets there are now fishing rods. And the ubiquitous Polo insignia (alligators are an extinct species out here) has been replaced by the welcome monotony of wetsuits worn by surfers, scallopers and windsurfers. On a brisk October day, the beaches and bays look as if they have been invaded by a colony of monsters from the deep.

With the onset of fall, smart restaurants and trendy boutiques close, some to open only on the weekends, others to give up the ghost along with their lease for good. Fall wipes out the transience of summer, dissolving the glitter, pace and even the sensuality.

"The summer is fraught with expectations and romance," says Larry Penny, a naturalist and North Fork native, who settled here eight years ago to save the South Fork from "imminent destruction."

"It's easy to be titilated by everything out here. It's not a passive environment. It's actually overstimulating. Then after Labor Day, there's this sudden stillness. It's such a relief. The discos disappear, the noise and traffic decrease, and the people drop away."

When he moved back here after several years in California and Oregon, Penny was struck by the similarities between the two coastal regions and their native inhabitants.

"In terms of the diversity," he says, "very few places have as varied flora and fauna as the East End and the West Coast. The natives are oriented to the land and soil. And farming and fishing are a common heritage."

When he's not teaching, lecturing or consulting on the flora and fauna of Eastern Long Island, Penny leads early morning nature walks for the South Fork-Shelter Island Nature Conservancy. The hikes are popular, attracting weekenders, retirees, families and recently arrived year-rounders bent on returning to the land, or at the very least learning something about it.

On his nature hikes, Penny singles out the common and endangered plant and animal species, trying to bring prospective nature lovers into harmony with their environment. He tells "some history, some secrets of the plant and animal communities, decribes some geologic land forms." His own enthusiasm for the unusual and nearly extinct varieties is such that he has often brought hikers to their knees to examine the last of a particular breed. During a recent walk through the Shinnecock Hills above Southampton "part glacial moraine, part dune, and covered with windswept vegetation," he found a blue curl. And in no time, the participants from the elderly to the young were eye level with a rarely seen three-inch-high plant.

In September, Penny says, you can see every kind of migratory bird that ever passes through the Eastern End of Long Island. Most of the shorebirds can be found in the harbors or inlets to the north or perched on sand flats to the south, created this time of year by "the bleeding of the ponds" which join them to the nearby ocean. The ponds have Indian names like Mecox, Georgica, and Sagaponack, and the Indians, Penny theorizes, probably showed the English, who settled the area in 1640, how the digging of a narrow trench opens the ponds to the sea. "The bleeding" refreshes the water, cleansing it of summer bacteria and contaminants, and also relieving the awful stench brought on by a long spell of hot weather. Some local residents compare the operation to the washing out of the summer people.

Bird watchers may find an unlimited variety of species in the Hamptons but a seeker after fall foliage will be disappointed. Instead of brilliantly colored leaves, at this time of year there is an almost palpable clarity of light. The sand is more beige, the water a true aquamarine, the sky a brighter blue and every object silhouetted against it becomes clearer and more concentrated, qualities that have attracted a large number of artists from abstract expressionists to objectivists and figurative painters. The community of artists here dates back to the 1950s when Jackson Pollack, Lee Krasner and William de Kooning settled in the Springs, north of Easthampton near Gardiners Bay. They were followed by Fairfield Porter, Larry Rivers, and Roy Lichtenstein who took up residence in the village of Southampton. Others are now scattered throughout the Hamptons.

Painter John Mac Whinnie has lived here since his teens and chose to remain because of the beauty of the environment and the community of artists. A student of the late Fairfield Porter (and like him a figurative painter whose work reflects much of that defined light) he inhabits a converted barn in Water Hill abutting 11 acres of farmland. His studio is at the back of the barn and opens onto a spectacular nuance of light and color.

"Summer's diffused blend of light changes in the fall when the light makes things more radical and distinct," he says. "Clouds are more intense. The blues in the sky separate into a high cerulean that turns turquoise lower down peeking through the clouds. The sea reflects that turquoise, the contrasts are clearer, and with every fall day comes a radical change in color."

That's a painter's version. A meteorologist would say that the clear warm days, enhancing and prolonging Indian summer here, are caused by the Bermuda high. This stationary air mass moving off the coast of Bermuda dries the air in the autumn, warms the days, cools the early evening, and when combined with the sea air prevents the leaves from turning more than a rusted brown.

In the fall, when he's not painting, Mac Whinnie takes his dinghy for short spins on the pond across the road from his house and hunts Indian artifacts on the mounds near Three Mile Harbor in Easthampton. Or he hikes through the wildlife preserves at Quoque and the Morton Wildlife Refuge in Southampton. Spreading out over 187 acres, the Morton Refuge has a mile long trail through the woods, opening out onto the beach at Little Peconic Bay. It's a favorite of children who can feed handfuls of sunflower seeds ("much in the manner of St. Francis," says Larry Penny) to the eager chickadees flocking around the entrance.

The inlet waters, somewhat warmer than the ocean, are good for bathing this time of year. Pebbles and shells cover the beaches, narrower and less inviting than the Atlantic sands. But they are ideal for observing bay life, especially twirled whelks and their snake-like brittle egg cases drying in the sun. And the inlets and bays in the fall are bountiful with scallops.

To many here, in fact, the opening of scallop season in mid-September marks the real beginning of autumn. Seven years ago during our first South Fork fall, year-round neighbors of ours introduced my husband, two children and myself to scalloping. It has since become an annual ritual. Since we use our neighbors' canvas-covered home-built canoe, we must wait for low tide, which usually occurs in the early afternoon, to begin our trip. The water, shore and sky are distinctly outlined and deeply colored. The thin-stemmed feather-tipped sea grass surrounding the bay bends and rasps softly. Overhead, the water birds, including a few ducks, alight on the water's surface. Wherever they cluster we can be sure to find scallop beds. We paddle out, three at a time, into the inlet, dropping our long-poled nets into the water and scooping up mud, stones, scallops and assorted unuseable bay life. The scallops, not giving up so easily, are still defiantly spitting water at us. It takes us most of the afternoon, to scoop, sift, sort and fill five buckets waiting on shore.

Along the way we search for beds, we encounter other scallopers remarkable for their practical costumes and inventive fishing devices. Some scallopers simply glide out in row boats. Others plod along in hip high waders. Still others can be seen floating in inner tubes with baskets attached and a common sight, favored by the old timers, is the glass bottom box, much like a giant pair of goggles moving along the surface of the water.

Richard Panobianco, who summered in Southampton as a child and returned to work here as a doctor, dives for his catch in a wetsuit. He spends two weeks of his vacation devoted solely to the pursuit of scallops. Aqua lungs, he says, are forbidden because of the heavy boat traffic and the effect on bay life. So he snorkels into 12 feet of water, scoops up the scallops in a gloved hand, then transfers the catch to the net in his other hand, and when the net is full, returns to shore to deposit them in a bushel basket. Once the basket is filled, the allotted quota, he heads for home.

After the catching comes the cleaning, an intricate and arduous operation. We have never learned the baymen's art of opening the scallop so that the tiny white morsel which lies attached to the shell by a thick orange muscle can be extricated in one swift movement of the knife. It is often late in the day by the time we get to the cleaning. The air by then has turned chilly, and we are struggling to open the shell and separate the much smaller scallop from its connecting tendon without cutting the flesh. We plan to have these scallops for dinner, and many hours later, along with numb and wounded hands to eat them with, we do.

Because we are limited to weekend scalloping, we may have one or at most two foraged meals. Other scallopers like the Panobiancos who harvest, and then freeze them, eat them all during the winter. Almost too much, says Panobianco's wife, Chris Thompson. "By February you don't want to see another scallop." But it's a far cry from the summerfolk, from that more typical Hamptonite who buys his meals at the pricey take-out shop in the village.