The last known dusky seaside sparrow has died in captivity at Walt Disney World, where scientists had hoped to save the species from extinction by cross-breeding it with similar sparrows.

Officials at the Florida amusement park's wildlife refuge said yesterday that the canary-sized bird, named Orange Band for a metal tag on its leg, was found dead in its food dish Tuesday. The bird was the last of five male duskies gathered from the wild in 1980 -- apparently the only birds remaining of a flock that once numbered in the thousands.

"As far as we know, there are not any more," said U.S. Fish and Wildlife Service spokeswoman Megan Durham. "This marks the extinction of the species. No females or evidence of reproduction in the wild has been seen since 1975, and this bird was more than 12 years old."

The death of Orange Band ends a last-ditch effort to save the dusky through cross-breeding. The male duskies had been mated to Scott's seaside sparrows; scientists hoped the resultant offspring could be mated again with the duskies to produce birds with ever-purer dusky bloodlines.

The experiment produced five part-duskies, one male and four females. One of the females is seven-eighths dusky, but the loss of the last pure dusky means that no offspring will ever be purer than that. Scientists still hope to repopulate the wild with the hybrid birds, which are fertile and look purebred.

Disney World curator Charles Cook said the last bird's heart and liver will be frozen in hope that technology will someday make it possible to recreate the species through cloning.

Once plentiful in Brevard County, Fla., where it lived in marshland along the St. Johns River, the dusky seaside sparrow fell victim to the advances of man.

The bird's sole habitat was 10 square miles of Atlantic marsh near Titusville, directly in the path of advancing development from the Cape Canaveral space complex.

Although similar habitat was available nearby, the dusky refused to move. Its stick-close-to-home character made it unique among North American birds and a favorite with visiting watchers. In 1947, Roger Tory Peterson's field guide said that "any seaside sparrow seen in the Titusville area in the summer is this species . . . . You will find it across the bridge."

By the 1960s, however, road construction and pesticide spraying had reduced the population to 2,000, and a mid-1970s wildfire wiped out many of those.

"From 1975 to 1980, the population was decreasing at a rate of 50 percent every year," Cook said. By 1980, when desperation forced ornithologists to capture the last birds for a breeding program, only Orange Band and his four male companions remained. They died at the rate of one a year starting in 1983.

Cook, who cared for the duskies at the Disney World refuge since 1983, said the loss of Orange Band was "sobering," but added that "the mood here has not been depressed."

Sadness at Orange Band's passing was quickly overcome by efforts to preserve its tissues for the future, Cook said.

"It felt like we shifted gears, and that became as important as the living bird, knowing those tissues were still alive," he said.

"People here feel that the dusky carried a banner, and the program gave the bird a chance to tell its story," Cook said.

"That bird could have become extinct seven years ago and gone entirely unnoticed. Its story gave everyone a chance to reflect on our own mortality and our effect on the environment."