BALTIMORE -- In a three-year-old federal program, about a dozen Cochin bantam chickens have been squatting on fragile eagle eggs in a climate-controlled coop at the Interior Department's Patuxent Wildlife Research Center in Laurel.

The eggs, which are incubated by hens up to the point of hatching, produce healthy eaglets more often than do artificial incubators and, in some cases, the mother eagles themselves. One of those eaglets released in Georgia recently bred successfully in the wild. The bird was the first to do so since the program started in 1984.

"We're hoping to {increase the bald eagle population}, but the jury is still out" on the program's success, said Rod Gable, aviculturist for the center's endangered species program and operator of the incubator program, believed to be the first of its kind for eagles.

The center, which also uses chickens to incubate eggs of endangered whooping cranes and Mississippi sandhill cranes, has released about 30 chicken-incubated eagles into the wild. Chickens were first used to incubate eggs of endangered peregrine falcons, which eat pesticide-laden food that leaves egg shells extremely thin and fragile.

Scientists at the Patuxent center faced the same problem with bald eagles. They also wanted to incubate eggs away from the mother so the endangered bald eagles, symbols of the nation's strength, could continue to lay eggs and increase their numbers.

"We found over the years that if you take some species' eggs immediately after they are laid and put them right into an incubator, that they don't do as well," Gable said. Only 60 percent of artificially incubated eggs bear live birds.

But the chickens hatched 93 percent of eagle eggs successfully the first year and about 80 percent yearly since then, about the same rate as the eagles themselves, Gable said.

The eagle eggs, about the size of very large chicken eggs, are removed from under the chicken to an incubator a few days before hatching. About a third of the eaglets are placed in the wild with childless adult eagles across the country. The rest remain in captivity at the center until they are ready to be released, Gable said.

"We are sort of an adoption agency for eagles," Gable said, adding that eagle chicks will be placed this year in New Jersey, Pennsylvania, New York, Tennessee and Georgia.

Scientists attribute the chickens' success to their lower weight, which is easier on fragile eggs, and to the fouls' unique distribution of heat unmatchable by an incubator, Gable said.