Science: Decline of the North American avifauna

		Science: Decline of the North American avifauna 分会秘书长：北京林业大学生态与自然保护学院丁长青/100083, Tel 010-62336869, Email:cqding@bjfu.edu.cn

Species extinctions have defined the global biodiversity crisis, but extinction begins with loss in abundance of individuals that can result in compositional and functional changes of ecosystems. Using multiple and independent monitoring networks, we report population losses across much of the North American avifauna over 48 years, including once common species and from most biomes. Integration of range-wide population trajectories and size estimates indicates a net loss approaching 3 billion birds, or 29% of 1970 abundance. A continent-wide weather radar network also reveals a similarly steep decline in biomass passage of migrating birds over a recent 10-year period. This loss of bird abundance signals an urgent need to address threats to avert future avifaunal collapse and associated loss of ecosystem integrity, function and services. DOI: 10.1126/science.aaw1313 https://science.sciencemag.org/content/early/2019/09/18/science.aaw1313 Fig. 1 Net population change in North American birds. (A) By integrating population size estimates and trajectories for 529 species , we show a net loss of 2.9 billion breeding birds across the continental avifauna since 1970. Gray shading represents ± 95% credible intervals around total estimated loss. Map shows color-coded breeding biomes based on Bird Conservation Regions and land cover classification . (B) Net loss of abundance occurred across all major breeding biomes except wetlands . (C) Proportional net population change relative to 1970, ±95% C.I. (D) Proportion of species declining in each biome.