Founded in 1883, the American Ornithologists' Union was one of the oldest organizations in the world devoted to the scientific study of birds. Over its history, AOU and its members helped create the scientific foundation for ornithology and bird conservation that we enjoy today. The AOU was the largest and most diverse ornithological society in the New World. Although primarily an organization for professional ornithologists, it welcomed to its ranks many students, conservationists, birders and others who cherish the birds of the world.
In 2016, The AOU merged with the Cooper Ornithological Society to form the new American Ornithological Society.