Fifteen amateur birders gaped in horror yesterday as a hungry laughing gull dove at a tiny feathered creature floundering in the Patuxent River. The thin little bird had just been banded by researchers and released back to the wild rice marshes of Jug Bay.

For a brief moment, it seemed as if nature would claim a bird whose population in the Washington area has barely survived suburban development and the carp and geese who gobble the wild rice plants that are staples of the bird's diet.

But as soon as Greg Kearns saw the bird was in danger, the Patuxent River Park naturalist turned the pontoon of birders toward the water-logged Virginia rail and leaned over the boat to scoop it to safety. After being deposited closer to land, the bird wobbled back into the dense vegetation where it hides during daylight.

"Poor baby," said Patsy Decker, a 48-year-old teacher from Salisbury. "You do wonder how they handle all of this. I wonder if they go back and tell the other birds, 'You won't believe what just happened to me.' "

Kearns, who has been researching the so-called sora and Virginia rail birds since 1987, was taking the birders on an expedition to find the elusive bird in the wilds of Prince George's County.

Years ago, he could have guaranteed an encounter with one on the mud flats. The freshwater marshes of the Patuxent were once the most famous rail hunting grounds in the Chesapeake Bay area, and the birds often were hunted by the likes of Teddy Roosevelt, Babe Ruth and Harry S. Truman.

The sport was so popular that a special boat was designed specifically for hunting rail birds. So-called pole pushers navigated the flat-bottomed vessels through the marshes for hunters trying to bag the coveted prey.

But the only rails taken yesterday were those Kearns and his research assistants lured with audio calls and captured in traps hidden in the marsh.

It was a treat when Kearns let the group of mostly middle-aged men and women take turns holding and stroking the birds that they usually encounter through a pair of binoculars.

"I've never held a bird," Decker said. "It's so soft and warm, and they're really light."

After measuring and weighing the birds, Kearns attached a radio transmitter to one. He and his research partner, G. Michael Haramis, a biologist at the U.S. Geological Survey, will use the device to better understand the migration of the birds.

"How do these birds get here and how do they find this marsh in the dark?" he said. "To me, it is a remarkable mystery."

Scientists hope that the birds' migratory patterns will tell them where the birds are finding their diminishing food sources. The sora rail, with greenish-yellow legs and white specks on its back, eats insects and snails. The Virginia rail, with brown legs, rust-colored patches on its wings and a longer beak, primarily eats wild rice.

The birds are endangered because freshwater marshes are becoming harder to find, and those with wild rice are even rarer.

Each fall, the birds frequent Jug Bay marsh for about six weeks, fattening up for the trip south. But the rice plants withered in the summer drought, then were overcome by the floods from Hurricane Floyd. As a result, scientists are seeing fewer rails this year.

Kearns said he has captured about 270 birds this year, compared with 1,000 by the same time last year.

"This has been the worst trapping year ever," he said.

But he is hopeful. One of the soras he weighed yesterday was a robust 89 grams, and Kearns rolled the fat on its breast between his fingers.

"When I see a spunky one like this, I feel good it's going to make it," Kearns said.

CAPTION: Susan Polniaszek, left, of Clarksville, holds a young sora rail as Linda Cashman, of Salisbury, takes her picture.

CAPTION: Naturalist Greg Kearns, who researches rails, measures a young sora rail. He then banded, weighed and placed a radio transmitter on the bird.