The United States is home to a tremendous diversity of native birds, with more than 800 species inhabiting terrestrial, coastal, and ocean habitats, including Hawaii. Among these species, 67 are federally listed as endangered or threatened. An additional 184 are species of conservation concern because of their small distribution, high threats, or declining populations. Successful conservation requires information about the population status of every species to ensure the survival of endangered birds and to manage common species so they never become threatened. This report presents a new synthesis of major bird-monitoring databases, including data from thousands of citizen scientists and professional biologists. We used data from three continent-wide monitoring programs to create bird population indicators for major U.S. habitats, reflecting the health of these habitats and the environmental services they provide. These habitat indicators are based on the population changes of obligate species - those that are restricted to a single habitat and are most sensitive to environmental changes. We supplemented this information with data from many other surveys that focus on species that are rare, endangered, or difficult to monitor, such as ocean birds. (See pages 33-34 for methods.) The results reflect the influence of human activities and global change on our nation's birds. Every U.S. habitat harbors birds in need of conservation. Hawaiian birds and ocean birds appear most at risk, with populations in danger of collapse if immediate conservation measures are not implemented. Bird populations in grassland and aridland habitats show the most rapid declines over the past 40 years. Birds that depend on forests are also declining. In contrast, wetland species, wintering coastal birds, and hunted waterfowl show increasing populations during the past 40 years, reflecting a strong focus during this period on wetlands conservation and management.