Large-scale conservation assessment for Neotropical migratory land birds in the interior Columbia River basin

The status and habitats of Neotropical migratory land birds (NTMB) are evaluated within the interior Columbia River basin (interior basin). Objectives are to examine population trends， estimate NTMB responses to alternative management activities， and provide recommendations by habitat and species for the long-term persistence of NTMB populations. Among 132 NTMBs that breed in the interior basin， 38 species showed significant population trends over two time periods， 1968-94 (26 years)， and 1984-94 (10 years). Fourteen species had significant declines over the 26-year period and 13 over the 10-year period; 13 and 12 species showed significant increases over those periods， respectively. Among 16 defined habitats， riparian vegetation was used by more species (64 percent) than any other habitat. Other habitats used by many species included young coniferous forest (38 percent) and old-growth/mature forest (35 percent). Nine habitats had more species with significantly decreasing than increasing populations (26-year period)， and seven habitats had more increasing species. Five habitats (riparian， old-growth forests， shrub-steppe， grasslands， and juniper) are identified for management priorities based on declines in species， vulnerability to human activities， and habitat loss. Among the four management themes considered， more species (63) were of high concern under consumptive management than any other theme. Active and passive management themes are predicted to have negative effects on the fewest species， 23 and 16， respectively.(Interior Columbia Basin Ecosystem Management Project: Scientific Assessment. Thomas M. Quigley， Editor)