North America's bird populations have declined significantly in the past 40 years as bulldozers have flattened forests, rolled over grasslands and filled wetlands, according to a study released Thursday that is the first comprehensive analysis of the state of the nation's birds.
About one-third of 800 bird species in the United States are listed under federal law as endangered or threatened, or are dropping in numbers precipitously, because of lost habitat, invasive species, polluted water and changing climate, said the study, by government wildlife agencies and conservation groups.
But efforts to restore nesting and feeding grounds, ban pesticides and halt development in sensitive wetlands and other migratory stopovers have brought back the California brown pelican, the peregrine falcon, the bald eagle and a bevy of herons, egrets, osprey and ducks, among other birds.
"Conservation can really work," said Interior Secretary Ken Salazar, who released "The State of the Birds" at an event at the National Press Club in Washington, D.C., attended by representatives of the American Bird Conservatory, the Cornell Lab of Ornithology, the National Audubon Society and other groups.
"There are places where many bird species are doing better today than we were 10 to 15 years ago," Salazar said. "Those success efforts should lead us to what we should be doing in the future."
Call to action
Still, the downward trend in numbers should set off alarm bells, said Salazar, who described the report as "a clarion call to action" to restore bird populations. "In 2009 it is time for a new beginning" on how to make sure wildlife and habitat are protected."
Salazar made his comments just days after environmental groups criticized him for announcing that the Interior Department will hold more than 40 major lease sales for oil and natural gas development on public land this year. They warned that the sales would jeopardize wildlife and wildlands.
The data analyzed for the assessment came from the U.S. Fish and Wildlife Service, U.S. Geological Survey and the Canadian Wildlife Service and included the North American Breeding Bird Survey as well as trends from 40 years of citizens' sightings gathered in the National Audubon Society's Christmas Bird Count.
This week, Audubon California, a branch of the national group, released its maps of 145 "Important Bird Areas in California" that support sensitive species and large numbers of species, including 21 areas in the Bay Area.
Birds that nest or rest on the nation's coasts, where nearly half the U.S. human population lives or works, are particularly imperiled, the government study said, because those areas are expected to grow by 25 million people by 2015.
Of 173 bird species that use the coastal habitats at any time of year, 53 are in trouble and 14 are listed as endangered or threatened, the study said, and 14 of 27 shorebird species that primarily use coastal habitats have declined.
Federal and state governments could offer incentives that protect coastal habitat for birds, and cities and counties could protect natural areas, the study recommended.
The study also found:
-- Beach-nesting birds, including snowy plovers and least terns, are vulnerable to people and pets that inadvertently destroy or disturb nests. In the Bay Area, those birds are found on Ocean Beach and Alameda.
-- The common murre remains one of the most numerous seabirds in the Northern Hemisphere, but local populations can be severely reduced by climate change, oil spills and nest predators. The birds, hit by the 2007 Cosco Busan oil spill in San Francisco Bay, nest on the Farallon Islands and Devil's Slide Rock on the San Mateo County coast.
"The snowy plover has become the poster child for the effects of beach disturbance on shorebirds," said Melissa Pitkin, education director at PRBO Conservation Science of Petaluma, which conducts research on birds, fish and mammals.
Still, plover populations are being held stable, or slightly increasing in some locations, because of fencing and other recovery efforts along the coast, she said.
Seabirds can suffer from sparse food supplies of krill and anchovies in the ocean during years of low upwelling, Pitkin said. Cassin's auklets have declined since the 1970s, experiencing complete nesting failures in 2005 and 2006 on the Farallon Islands, when ocean waters were warmer.
Common murres have increased in numbers on the islands over the past eight years, but are now leveling off, she said.
One of the challenges in preparing the study was the lack of centralized data for trends in shorebird populations, Pitkin said. Data exist from a few sites, including many federal wildlife refuges, "but it is not pooled together - and accessible - to really know if shorebird species are increasing or decreasing," she said.
As a result, PRBO and its partners have created an avian data center to collect information in California.
How America's birds are faring
Read the study at www.stateofthebirds.org.