Founded in 1883 for the furtherance of scientific ornithology, its organ being The Auk. These papers consist of bylaws, lists of officers and members, program announcements and financial statements. Correspondence about the activities of the Union stresses the publication of The Auk, check lists of birds and the awarding of its medals. The names most frequently appearing are Louis B. Bishop, Jonathan Dwight, Jr., Joseph Grinnell, A.H. Howell, W.L. AcAtee, Harry C. Oberholser, John H. Sage, Witmer Sone, A.E. Urban (for the Intelligencer Printing Company) and Alexander Wetmore.

The number is estimated only, with not list of signers given.

Gift of C.M.B. Cadwalader, as a part of W. Stone's papers, 1939