Birds of North America (BNA)
A comprehensive reference covering the life histories of North American birds. Contents are updated frequently, with contributions from researchers, citizen scientists, designated reviewers and editors. In addition, BNA Online contains image and video galleries showing behaviors, habitat, nests, eggs and nestlings, and more. Each online species account contains recordings of that bird's songs and calls, selected from the extensive collection in Cornell's Macaulay Library of Natural Sounds.