Data sources for information on bird abundance and distribution at a variety of spatial and temporal scales. (Cornell Lab of Ornithology and National Audubon Society)
Joint membership service of the American Ornithologists' Union (AOU), Association of Field Ornithologists (AFO), Cooper Ornithological Society (COS), Raptor Research Foundation (RRF), Waterbird Society (WS), and Wilson Ornithological Society (WOS).