NEW YORK - For decades unseen within Central Park's 840 acres, the Eastern screech owl has found a home again in sight of skyscrapers and the lights of Times Square.

The revival was orchestrated by the city Parks Department, which is financing an ambitious plan to reintroduce to city parks native species such as the beer-can sized owls.

Nearly 40 owls have been released in several groups in the park since 1998, but it was only this year that a mating pair produced the first homegrown offspring - two owlets, the first verified nesting in the park since the mid-1940s.

"We are trying to take parks to a new level," said Alexander Brash, chief of the Urban Park Service, which is overseeing the release and monitoring of the owls. "Central Park could become a source for screech owls to populate other city parks."

But while Brash and the park service are devoted to restoring the tiny owls, others might be inadvertently threatening them.

Millions of pounds of pesticides are used in the state each year to kill insects, rodents and other pests that infest and damage homes, gardens and buildings.

In the fight against rats and mice, government agencies such as the Transit and Housing authorities and the city Sanitation Department make regular use of rodent poisons that, in turn, can enter the food chain.

Mice and small rats are the screech owl's favorite food.

State records show that one of the city's screech owls, found dead near 72nd Street in January, ate the wrong rodent. It's the first time the death of one of the park's owls has been connected with rat poison.

State reports

Investigators determined the owl was killed by "rodenticide poisoning with Brodifacoum," a chemical in rat poisons, including some of those used by the Sanitation Department. "This owl appeared ready to start laying eggs," noted a report by the state Department of Environmental Conservation.

State files are replete with examples that conclude birds of prey were felled by pesticide poisoning in New York City: red-tail hawks, American kestrels, a long-eared owl.

"I think there is a huge pesticide problem out there," said Ward Stone, a state wildlife pathologist who took part in a 1999 study that linked 26 deaths of owls, hawks and eagles to likely anti-coagulant rat poisons, which cause hemorrhaging.

"When pesticides kill owls, it's killing the very thing that should not be harmed, because owls are going to control the rats and mice," Stone said. "We certainly need to have rat and mouse control, but we need to gear up our industries to come up with safer pesticides."

The city Parks Department at times has restricted, but not eliminated, the use of rat poisons within parks, officials said. But researchers tracking the owls with radio transmitters have found the birds frequently prowl the streets far beyond Central Park's boundaries, where no such restrictions apply.

The owls "are out on the streets foraging for rats and mice at night," said William Giuliano, an ecologist at Fordham University, which is studying the park's screech owls. With rodenticides in wide use, "That's certainly a concern."

Industry groups say the products are safe and effective when used correctly. They argue that deaths of other animals can often be incorrectly attributed to the chemicals.

"These are highly effective products and have been around for years," said Lynn Bergeson of the Rodenticide Registrants Task Force, a manufacturers group.

But even without the threat of a last supper on a poisoned mouse, the owls face a daunting challenge to survive. In areas where the owls are known to thrive, as many as seven in 10 may not live through their first year.

Of the 38 owls released in Central Park since 1998, and the two youngsters hatched this year, researchers can locate only nine, although they estimate as many as a dozen may be in the park. Seven are known to have died.

Raptor Trust balks

The Raptor Trust, a New Jersey bird rehabilitation center that supplied the first six owls released in 1998, declined to send more birds because of concern over rat poisons used by the city.

"I was asked to continue the program after 1998 and I declined, because as I understood it they had reinstituted the use of poisons in the park," said Len Soucy, the president of the trust.

"You can't be pro-owl and support the wholesale poisoning of rodents," he said.