American Birding Association
American Ornithologists' Union
Archaeopteryx Resource Page
Association of Field Ornithologists
Bird Songs
Birding.com
Birdnet
Birds of North America, Life Histories for the 21st Century
BirdSource
Breeding Bird Survey
Bring Back the Whooping Cranes
Cooper Ornithological Society
International Crane Foundation
North American Bird Sounds
Operation Migration
Ornithological Council
Ornithology: the science of birds
Partners in Flight
Raptor Research Foundation
Smithsonian Institute
U.S. Fish & Wildlife
Wilson Ornithological Society
Wings of the Americas
Writing of Henry D. Thoreau