November 29, 2007—More than a quarter of U.S. birds are at risk of extinction, says a study released today by the nonprofit groups National Audubon Society and the American Bird Conservancy.

Some 178 species in the continental U.S. and 39 in Hawaii appear on the WatchList 2007, which the groups say is one of the most comprehensive analyses of national bird data in the past five years.

The report blames habitat loss, pollution, invasive species, and global warming for the species decline.

But conservation programs can work effectively, the study adds. At one time California condors, such as the one seen here, were down to just nine individuals.

But the raptor now numbers above 300 because of captive breeding and other preservation efforts.

The species still teeters on the brink however, the report says—since lead bullet fragments from hunters continue to poison many of the birds of prey. The threat spurred the recent passage of a state bill banning such ammunition in condor habitat.

—Aalok Mehta

• More Photos in the News
• Today's Top 15 Most Popular Stories
• Free Email Newsletter: "Focus on Photography"