Peregrine Falcons, once teetering on extinction, are regulars at Acadia National Park. Bald Eagles, also once feared to be ready to blink out, have rebounded incredibly and are highly visible in many national parks.

During a week-long canoe trip in Yellowstone National Park last fall I was blown away by the birdlife. We saw Bald Eagles whose wingspans seemed close to or greater than 6-feet from wingtip to wingtip. On occasion we saw Osprey, some in the course of hunting Yellowstone Lake's waters for trout. Sandhill Cranes woke us regularly with their chortling. American White Pelicans were common, as were various species of waterfowl.

But how is the overall "state of birds" in America these days? Unfortunately, things aren't entirely as they appear.

Oh, there are some great recovery stories out there, such as the Peregrine Falcon and the Bald Eagle. And strides are being made in habitat restoration and conservation. But much work remains to be done.

According to the first-ever State of the Birds, a 36-page report compiled by the North American Bird Conservation Initiative, American Bird Conservancy, Association of Fish and Wildlife Agencies, the Cornell Lab of Ornithology, the Klamath Bird Observatory, the National Audubon Society, The Nature Conservancy, the U.S. Fish and Wildlife Service, and the U.S. Geological Survey, nearly one-third of the country's 800 bird species are either endangered, threatened, or in significant decline.

The problem? Loss of habitat, invasive species, pollution, and growing climate-change impacts.

"Just as they were when Rachel Carson published Silent Spring nearly 50 years ago, birds today are a bellwether of the health of land, water, and ecosystems," says Interior Secretary Ken Salazar. "From shorebirds in New England to warblers in Michigan to songbirds in Hawaii, we are seeing disturbing downward population trends that should set off environmental alarm bells."

How dire are things?

* 71 bird species native to Hawaii have gone extinct since the islands were colonized by humans back about 300 A.D. At least 10 more bird species haven't been seen in as long as 40 years, and just might be extinct as well.

* Nearly 40 percent of bird species that call oceans their habitats are declining, in part due to pollution, over-fishing that deprives them of food, and warming sea temperatures attributed to climate change.

* Half of all coastally migrating shorebirds have declined. Red Knots, a colorful shorebird that once was an easily spied species along the East Coast, have declined by 82 percent.

* Move inland, and the report tells us that nearly half of the 46 species of grassland-breeding birds are species of conservation concern, and four of those are listed as endangered under the Endangered Species Act.

* Head into the country's forests and you'll find that, of 310 forest-breeding birds found across the country, 22 percent are species of conservation concern and 11 are listed as either threatened or endangered under the ESA.

Fortunately, those statistics don’t tell the entire story. They don’t point to the success stories, many of which are occurring with thanks to the National Park System. And that shouldn’t be surprising at all, when you consider the vast array of biological diversity and habitat that can be found within the system.

“Channel Islands (NP) is one of those Park Service units that have been doing some really exciting work,” says Carol Beidleman, who heads the agency’s Park Flight Migratory Bird Program. “One of their areas of emphasis has been removing non-native species. For instance, the non-native black rats on Anacapa Island. They’ve been working on that for a number of years and they are starting to see the results. There’s been a real positive response by Xantus’s Murrelet, a very rare seabird which nests on that island.

“And they’re engaging with a larger Seabird Group of people who are working together. They’ve also done some restoration of seabird habitat on Santa Barbara Island, and restoration of Ashy Storm-Petrels on Santa Cruz Island, so they have some very good success stories there,” she says.

Everglades National Park, even though it’s struggling to get its ecosystem back on track via the Comprehensive Everglades Restoration Plan, remains one of the world’s most incredible subtropical ecosystems. Indeed, the park comprises the largest subtropical wilderness area in the Northern Hemisphere, and the ecosystem is spread across marshes, hardwood stands, mangrove swamps, and more. That’s all wonderful bird habitat.

“The Everglades is the only National Park (by that designation) in the Ramsar sites in the U.S.,” says Ms. Beidleman, referring to the Ramsar Convention on Wetlands, a 38-year-old international effort to conserve wetlands and their resources. “It’s huge relative to all the other Ramsar sites in the U.S., so it’s really significant. The park supports about 150 species of waterbirds, shorebirds, and waterfowl that are using those wetlands, so it’s a bright spot.”

A surprising grassland success story is at Cuyahoga Valley National Park in Ohio, just south of Cleveland.

“We work closely through the Park Flight Migratory Bird Program with Cuyahoga Valley National Park. Some people think of it more like an urban park, but they had a really neat project there, working with their environmental education center, to restore an area that was formerly a coliseum,” explains Ms. Beidleman. “This was a massive, cemented, paved over area, a sports arena, and it was actually demolished and restored to grasslands which they had there before. Now they’ve documented the return of Henslow’s Sparrow, Bobolink, and Grasshopper Sparrow, all species of conservation concern in that area.”

If you read the State of the Birds report, you'll find many more instances where bird species are struggling to survive. But there also are success stories evidenced not just by Peregrine Falcons and Bald Eagles but also Trumpeter Swans, and wetland species have been growing in number thanks to habitat restoration work.

"These results emphasize that investment in wetlands conservation has paid huge dividends," says Kenneth Rosenberg, director of Conservation Science at Cornell's Lab of Ornithology. "Now we need to invest similarly in other neglected habitats where birds are undergoing the steepest declines."