Note: This page is about the history of AOS. For resources about the history of ornithology in general, visit the AOS History Committee page.

The American Ornithologistsā€™ Union (AOU) was founded in 1883 by William Brewster, Elliott Coues, and Joel Allen out of concern for bird conservation and interest in developing the field of ornithology in North America. Early AOU efforts led to formation of the National Audubon Society and the Biological Survey (now known as the U.S. Fish and Wildlife Service). Before merging with the Cooper Ornithological Society to form the American Ornithological Society in 2016 (see below), the AOU was the largest ornithological society in the Western Hemisphere and one of the oldest organizations in the world devoted to the scientific study and conservation of birds. The AOU archives are housed at the Smithsonian Institution, and a history of the society’s first century was published in 2016.

The Cooper Ornithological Society (COS) commemorated an early western naturalist, Dr. James G. Cooper, and grew from a small band of naturalists in 1893 to an internationally recognized scientific society. The COS was committed to advancing the conservation and management of bird species by applying high-quality science, grounded in natural history, to our understanding of avian biology. The COS archives are housed at several institutions:

Effective 11 October 2016, these two societies merged to form the American Ornithological Society, now the world’s largest professional organization for ornithologists. Join us today!