In 1905, the AOU held its 23rd annual congress in New York City and published volume 22 (new series) and volume 30 (old series) of The Auk. Charles B. Cory entered his second year as president, and C. F. Batchelder and E. W. Nelson continued as vice-presidents. John H. Sage entered his 16th year as Secretary, and Jonathan Dwight, Jr., served his second year as Treasurer. The Council consisted of seven additional members and five ex-presidents. J. A. Allen continued as Editor of The Auk for his 22nd volume, and Frank M. Chapman was Associate Editor. There was a Committee on Publications and a Committee on Arrangements for the meeting in 1905, both chaired by President Cory.

The membership was 860 individuals in five categories: 45 Fellows (14 of whom were founding members and 3 of whom were Life Members [William Brewster, Charles Cory, and John Sage]), 18 Honorary Fellows (including Alfred Russel Wallace), 65 Corresponding Fellows, 71 Members, and 661 Associates. During the year, the Union lost 58 members: 5 by death, 27 by resignation, and 26 for nonpayment of dues. In 1905, Walter Faxon was no longer considered a Fellow, a fact mentioned in his obituary published in The Auk in 1921 (38:157–158), but without explanation. Mr. Faxon, as he preferred to be called, was Curator of the Invertebrate Department at the Museum of Comparative Zoology from 1874 until his death in 1920. His ornithological claim-to-fame was his demonstration in 1913 that “Brewster's” Warbler was a hybrid between Blue-winged Warbler (Vermivora pinus) and Golden-winged Warbler (V. chrysoptera) warblers.

The 23rd congress was called to order by Vice-President Batchelder on Monday night, 13 November 1905, at the American Museum of Natural History (AMNH). He was elected President; E. W. Nelson and Frank M. Chapman, Vice-Presidents; John H. Sage, Secretary; Jonathan Dwight, Jr., Treasurer; and Ruthven Deane, A. K. Fisher, Thomas S. Roberts, Witmer Stone, William Dutcher, Charles W. Richmond, and F. A. Lucas were elected members of the Council. The report of the Treasurer showed the finances of the Union to be in a satisfactory condition, much better than ever before.

Charles W. Townsend, John E. Thayer, Reverend William Leon Dawson, James H. Riley, and Austin H. Clark were elected to the class of Member, and 71 persons were elected Associates. Walter K. Fisher (1878–1953), Lynds Jones (1865–1951), and Wilfred H. Osgood (1875–1947) were elected Fellows. Fisher-son of Albert K. Fisher (1856–1948), who helped found the AOU and served as President-had a distinguished career as a Professor of Zoology at Stanford University and was instrumental in the early years of the Cooper Ornithological Club (COC) and the early beginnings of The Condor (see Fisher 1940). Osgood started the COC while an undergraduate at Stanford University and served as the first President. He went on to have a dual career in mammalogy and ornithology, eventually becoming Curator of Zoology at the Field Museum of Natural History in Chicago. Jones was a Professor at Oberlin College in Ohio and offered the first college course in ornithology in the United States, in 1895. He founded The Wilson Bulletin in 1888 and helped start the Wilson Ornithological Club, serving as President (1927–1929).

The following morning, the first day of the meeting was called to order by President Batchelder, and an address of welcome was made by Professor H. C. Bumpus on behalf of the President and Trustees of the AMNH. Papers read that day included “The evolution of species through climatic conditions” by J. A. Allen. In the evening, the members of the Union, and their friends, met at dinner at the Hotel Endicott. After dinner, an informal reception was held at the AMNH. Papers read the second day included “Some observations on the applicability of the mutation theory to birds” by Witmer Stone, “Discontinuous breeding ranges” by Wells W. Cooke, and “The principles of the disguising coloration of animals,” by Abbott H. Thayer. The morning session on the third day was held at the Museum, but the afternoon session occurred at the Brooklyn Institute of Arts and Sciences, with Frederic A. Lucas, Curator-in-Chief of the Museum of the Brooklyn Institute, Chairman. In the morning session, Dr. Palmer read a paper, “Should bird protection laws and their enforcement be in the hands of the national government?” by Otto Widmann, whom could not attend the meeting. (It was not recorded what the answer to that question might have been.) At the conclusion of the papers in the afternoon, there was an informal gathering in Lucas's office of the Curator-in-Chief, with refreshments provided by members of the Executive Committee of the Institute, with the opportunity to view the collections of the Museum. The next day, many members visited the Aquarium and the New York Zoological Park, where they were received and entertained by directors Hornaday and Townsend, and Curator Beebe. It was decided that the next meeting of the Union would be held in Washington, D.C.

There was also a report concerning the Fourth International Ornithological Congress:

“The Fourth International Ornithological Congress was held in London, June 12–17, 1905, under the presidency of Dr. R. Bowdler Sharpe of the British Museum (Natural History). The Congress opened with an informal reception at the Imperial Institute on the evening of Monday, June 12, followed by daily sessions on Tuesday, Wednesday, Friday, and Saturday. Thursday was given over to an excursion to Tring, where the members of the Congress were guests of the Hon. Walter Rothschild. On Friday afternoon the members were tendered a reception by the Right Hon. the Lord Mayor of London at the Mansion House, and in the evening were given a dinner by the British Ornithologists' Union. On the evening of Wednesday a conversazione was held at the Natural History Museum. After the adjournment of the Congress excursions were made on Monday, June 19, to the Duke of Bedford's Park at Woburn; on Tuesday to Cambridge, where Professor [Alfred] Newton welcomed the members of the Congress, and luncheon was served at Magdalene College; on Wednesday an expedition was made to Flareborough Head in Yorkshire, the breeding place of many sea birds. The Congress was marked by a large attendance of members, and the presentation of many noteworthy papers, and altogether was an occasion long to be remembered by those participating in its proceedings, and especially by the visiting member for the bountiful hospitality extended to them. In addition to the general meetings, the Congress was organized into sections, as follows: (1) Systematic Ornithology, Geographical Distribution, Anatomy and Paleontology; (2) Migration; (3) Biology, Nidification, Oölogy; (4) Economic Ornithology and Bird Protection; (5) Aviculture. It is impracticable at the data of this writing to give any account of the papers presented, which we hope to do in a later issue of this journal. Among the members of the A. O. U. present were the Misses Florence and Maria R. Audubon, Frank M. Chapman, Dr. J. Dwight, Jr., James H. Fleming, and Dr. L. Stejneger. Papers were presented by Chapman, Dwight, and Fleming.”