On a small island in Barnegat Bay, hundreds of birds that didn't exist in New Jersey 30 years ago bask in the summer sun.

Suddenly, they all take flight, oddly elegant and vaguely prehistoric, with 6-foot wing spans and the most recognizable bills in the animal kingdom. They are brown pelicans, described by naturalist John James Audubon as one of America's "most interesting birds."

They are also one of the Jersey Shore's newest residents, joining other top-of-the-food-chain bird predators including the peregrine falcon, the osprey and the royal tern to form a new avian golden age on Barnegat Bay.

Their ascendancy, however, is overshadowed by new federal research that names Barnegat Bay as one of the most distressed coastal estuaries in the nation.

"It's ironic that big birds are making a comeback at a time when the bay is edging toward disaster," said Suzanne Bricker, lead scientist for the estuary study conducted by the National Oceanic and Atmospheric Administration. "To save the birds, you have to save the bay."

Located just inside the barrier islands on the Central Jersey coast from Mantoloking south to Long Beach Island, Barnegat is one of the most productive ecosystems on earth and one of 28 estuaries deemed of "national significance" by the EPA.

One hundred fifty years ago, the bay was a paradise, biologists say. Shallow, clean, teeming with life, it attracted ducks, geese and wading and diving birds by the millions.

But relentless hunting brought many of the birds to the brink of extinction by the beginning of the 20th century and after World War II, the insecticide DDT nearly finished off the apex predators.

By 1970, peregrine falcons and all but one colony of osprey had disappeared from Barnegat Bay. Pelicans, considered annual visitors but not natives, were long gone and struggling to escape extinction in other parts of the country.

A DDT ban, cleanup of toxins and careful stewardship by the state Division of Fish and Wildlife brought the osprey and falcon populations back to health. The pelicans - originally native to the southern East Coast and Gulf states - showed up on their own.

"The pelicans started showing up about 25 years ago, and began nesting about 15 years ago, although we haven't yet found an egg in any of the nests," said retired biologist and Toms River native Fred Lesser, who with noted Rutgers behavioral ecologist Joanna Burger, has been studying the Barnegat avian population for 35 years.

"The pelicans seem to be coming earlier and staying later, so I'd like to say it's just a matter of time before they move in completely, but they don't seem in any rush," Lesser added. "But they have already nested in Maryland, and I see no reason why New Jersey wouldn't be next."

In the meanwhile, earlier erratic migrations seem to have settled into a steady, slowly rising population of pelican summer visitors on the bay.

They can be found hunting for menhaden and mullet throughout the bay, but their favorite roost seems to be a small, uninhabited, no-name island in the shallows off Island Beach State Park.

The island was man-made, built with sand dredged out of the Barnegat Inlet, that engineers had no place else to put.

They dumped it in a channel near Sedge Island, Lesser said, and nature did the rest. Vegetation blew in and took root. Predators, such as raccoon and fox, were stuck on the mainland. Humans ignored the bland little island.

The pelicans had a new home.

They can be found there most days in July and August, sunning themselves along with terns, gulls, herons, ibis and a variety of other birds.

The pelicans are unmistakable. The males and females look alike, with large, gray-brown bodies, dark brown and pale yellow heads and webbed feet.

The bird's most distinguishing feature, however, is its bill. It is pale, 18 inches long and connected to a large pouch that can hold up to 3 gallons of water and fish.

The brown pelican feeds by soaring 30 to 60 feet in the air, then plunging, bill-first, into the water. The impact would kill an ordinary bird, but pelicans are equipped with air sacs just beneath the skin to cushion the blow.

Firmly established as tourists, the question is whether pelicans will become permanent residents.

Bricker, at NOAA, is doubtful. Recreational overuse of the bay and overdevelopment inland from the bay are directly affecting the nutrient load in the water. "On the current trend, it is only a matter of time before vulnerable populations of sea grass and fish die off.

"There is tremendous pressure on Barnegat, and it shows," Bricker added. "Although New Jersey did a good job of cleaning up point-specific pollution, nonpoint pollution is doing so much damage that the bay ranks up there with dead zones in the Gulf of Mexico."

One surprising finding of the NOAA study was that agricultural runoff was not the primary source of nutrient pollution in the bay. A bigger culprit is the combustion engine.

Car, boat and power equipment engines produce nitrogen oxide which, when dissolved in water, reduces oxygen levels needed to sustain underwater grasses which, in turn, support the bottom-feeder population of Barnegat Bay.

Add in phosphate- and nitrogen-loaded stormwater runoff from thousands of houses built in the Barnegat watershed in the last 50 years, and the result is a bay with "serious eutrophication problems, algal blooms and a major decline in the fishing population," according to the study.

Burger, at Rutgers, believes the apex birds will adapt to changing fish populations, "as long as food is plentiful" for the pelicans, falcons and osprey.

Don Freiday, director of birding observation for the New Jersey Audubon Society, disagrees: "If there were trouble in the (condition) of the bay, it would show among the apex predators first. They won't die off; they'll just leave."

Both agree that nutrient contamination of the bay is a byproduct of one thing that can seriously hurt the birds: human encroachment.

"Even people who are not trying to harm the birds do so by their very presence," Burger explained. "They try to get closer for a better look, and spook the birds, driving them from their nests. That leaves eggs and chicks exposed."

They also agree with Fish and Wildlife expert Jim Sciascia that the future of the bay, and its birds, depends on education.

Sciascia, former head of the state nongame and endangered species program, makes biannual pilgrimages to the Sedge Islands in Barnegat Bay, in part because the "wildlife out here is so incredible. "

"People have to realize that they do have an impact, that what goes on your lawn or comes out your car goes directly into the bay," said Sciascia, now director of education and information for Fish and Wildlife, said, as he slowly toured the bay in a shallow boat. "These birds represent what is so amazing about New Jersey.

"We can't stop development," he added. "But maybe we can find a balance."

1. Brown pelicans take flight Sunday in Barnegat Bay, where hundreds of the birds have found a new home after decades of absence. 2. Jim Sciascia of the state Division of Fish and Wildlife tours Barnegat Bay's Sedge Islands, where he says the wildlife is "so incredible." MAP: Brown pelicans find new home in Barnegat Bay

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