NEW YORK – More than one in four U.S. bird species is declining in numbers or at risk of disappearing, according to a new report from the National Audubon Society.

The bird conservation group estimates that 201 species in the United States – including 20 that regularly appear in Maine – are menaced by habitat destruction, pollution, diseases and other threats.

The at-risk species in Maine vary from piping plovers to olive-sided flycatchers.

Among the most imperiled nationally is the short-eared owl, which has seen a nearly 70 percent population decline since the 1960s because of grassland destruction and the ingestion of poisoned mice and rats, Audubon spokesman John Bianchi said Tuesday, when the report was released. There are perhaps 100,000 short-eared owls left in the United States, he said.

The cerulean warbler, a deep-blue bird once found throughout the Ohio and Mississippi river valleys, has suffered a more than 70 percent decline, and it’s unknown how many are left, Bianchi said.

The birds’ conditions, worrisome on their own, should be taken as a broader indication of the health of the country’s ecosystem, despite successes such as the recoveries of the bald eagle and peregrine falcon, the group said.

“Birds warn us about disease, and birds warn us about the quality of our coasts and our oceans and our forests,” Audubon science director Frank Gill said at a Manhattan news conference releasing the group’s “Watchlist 2002.”

The 600,000-member National Audubon Society was founded in 1905 to protect birds and their habitats.

Maine’s at-risk birds include purple sandpipers, whimbrels, short-billed dowtichers, red knots, Nelson’s and salt marsh sharp-tailed sparrows, bay-breasted warblers and Bicknell’s thrushes.

Jody Jones, an ecologist at the Maine Audubon Society, said the at-risk birds can be found from the beaches on the southern coast to the mountains in western Maine to the forests in the northern reaches of the state.

Audubon officials urged people to cut back on pesticides and other poisons and to use more native plants in their yards, providing more food and shelter for birds.

“We can’t take the birds that we know so well for granted,” Gill said.

The Audubon Society assessed the more than 800 types of birds ordinarily found in the United States.

The Audubon endangered list contains about twice as many species as the federal list of threatened and endangered species.

Jeff Wells, the society’s bird conservation director, said political disputes among environmentalists, federal regulators and other interest groups kept many worthy species off the U.S. list.

A U.S. Fish & Wildlife Service spokeswoman had no immediate comment.