WASHINGTON - Amid the patches of woods and suburban parks that dot Triangle neighborhoods, a small brown-and-white songbird calls a melodic "ee-oh-lay" to area residents.

The wood thrush nests low to the ground, flits through woods near creeks and has seen its population in North Carolina plunge nearly 70 percent in the past four decades as forests fall and noxious chemicals taint the air.

Nearly one in four birds in the continental United States -- 178 species -- is at similar risk, according to a report Wednesday from two national bird conservation groups. Nearly a third of those -- including the wood thrush -- can be found in North Carolina.

The 56 species range from the golden-winged warbler in the mountains to the endangered piping plover on the Outer Banks. They are among those listed in a watch list from the National Audubon Society and the American Bird Conservancy, compiled through four decades of data from the annual Christmas bird count and breeding bird survey.

Also, 39 species from Hawaii are on the watch list.

Each species at risk has its own set of hazards, including sprawl, habitat loss, air pollution and global warming. But most of them can be traced back to human influence, Audubon officials say. More important, they say, are what birds can tell humans about the health of our environment.

"Their fate is determined by human activity more than anything else," said John Flicker, president of the National Audubon Society in New York City. "Their fate tells us about the threats to our habitats and quality of life."

Noticeable shift

Watchers have noticed the drop in bird numbers.

Lena Gallitano of Raleigh goes to Falls Lake every winter to conduct a Christmas bird count and said it's getting harder to find the little wood thrush with its flute-like call.

"Where we might have seen a few in the past, it's down to one or two now," said Gallitano, who serves on the executive committee of the Carolina Bird Club.

"To me, it means that it's getting more and more difficult for birds to, quote, make their living," she said. "They need certain things to live their life. They're finding it more difficult to find those things."

In two decades of watching birds from her back yard and during international trips, Gallitano has noticed how habitat destruction affects bird populations.

"It's not just Raleigh, North Carolina. It's all over the place," she said. "And the world is changing. Habitats are going away."

The wood thrush, for example, has lost nearly 65 percent of its population in the past four decades, hurt by forest fragmentation, cutting of trees for development, and predators such as raccoons, skunks and deer.

The bird also suffers the effects of acid rain on land snails, a major food source.

Snails offer the calcium females need to lay hardy eggs, said Curtis Smalling, important bird area coordinator for Audubon North Carolina.

Smalling said conservationists were shocked when they realized that merely protecting the wood thrush habitat wouldn't be enough to save the species.

"The air pollution was really striking," Smalling said. "Just drawing a line for some of these species is not sufficient. For a while we thought we'd done our job."

No 'magic bullet'

The federal Fish & Wildlife Service has its own watch list, including birds officially designated as endangered or threatened.

But the bird conservation groups said Wednesday the list is outdated, though they added that they are working closely with federal officials.

In some cases, state and local agencies can do more without the federal government, said David Pashley, director of conservation programs for the American Bird Conservancy. The Endangered Species Act "is not a magic bullet. It's not going to cure all of these problems."

Goal is one list

In North Carolina, the wood thrush is one of five species that the state Audubon organization has signaled out for special conservation attention. The others are the piping plover -- which is on the federal endangered species list -- and the seaside sparrow at the coast, the Bachman's sparrow in the sandhills and the golden-winged warbler in the mountains.

Near the coast, the seaside sparrow bathes in shallow salt marshes as sea levels rise and development cuts off its habitat.

Just 61 pairs of piping plovers were counted at the Outer Banks this year, Smalling said.

In the sandhills, the Bachman's sparrow searches for space among the pines as the fires it used to thrive on are increasingly suppressed.

And in the mountains, the golden-winged warbler is, like other birds, seeing its habitat affected by development and air pollution.

Other bird species fell off the group's watch list because they have recovered.

And one endangered species in North Carolina, the red-cockaded woodpecker, isn't among the state's top concerns because its population has stabilized, Smalling said.

Conservationists said they want to get organizations, bird watchers and government agencies focused on the same list of species in need.

"These birds will continue to decline and eventually fade into extinction if we do not act to make the watch list an action agenda," said Greg Butcher, director of bird conservation with Audubon.

The group has pushed for national legislation in Washington. In Congress, for example, the Senate is considering funding a program in the farm bill that helps farmers protect habitats for threatened bird species.

It also encourages conservation partnerships, pointing to success stories in major cities such as Chicago and Toronto.

"Even city dwellers live in nature," Butcher said. "It turns out that what's good for birds ends up being very, very important for humans."