In 1906, the AOU held its 24th annual congress in Washington, D.C., and published volume 23 (new series) and volume 31 (old series) of The Auk. C. F. Batchelder had become President at the November 1905 meeting and continued as President in 1906, E. W. Nelson continued as Vice-President, and Frank M. Chapman had been elected Vice-President in November 1905. John H. Sage entered his 17th year as Secretary, and Jonathan Dwight, Jr., served his third year as Treasurer. The Council consisted of seven additional members and six ex-presidents. J. A. Allen continued as editor of The Auk for his 23nd volume, and Chapman was Associate Editor. There was a Committee on Publications and a Committee on Arrangements for the meeting in 1906, both chaired by President Batchelder. Allen, Dwight, C. Hart Merriam, William Brewster, Charles W. Richmond, Robert Ridgway, and Witmer Stone were reappointed to the Committee on Classification and Nomenclature of North American Birds.
At the start of the annual meeting, the membership was 850 individuals, down 10 from the year before, in five categories: 48 Fellows, 16 Honorary Fellows, 60 Corresponding Fellows, 73 Members, and 653 Associates. During the year, the Union lost 68 members: 13 by death, 31 by resignation, and 24 for nonpayment of dues. No Fellows died in that year, but two Honorary Fellows passed away. Jean Louis Cabanis (1816-1906) died in Berlin, where he was Head of the Bird Collection of the Berlin University Museum until 1880, and Secretary of the German Ornithological Society until 1893. In 1847, he proposed a new classification scheme for birds in his publication Ornithologischen Notizen. In 1853, he started Journal für Ornithologie and was editor for the next 40 years until he was replaced by his son-in-law, Anton Reichenow (1847-1941), who also replaced Cabanis as Head and Secretary. An authority on African birds, Reichenow edited the journal until his retirement in 1921 and was also an Honorary Fellow in the AOU, having been elected in 1891. Another Honorary Fellow, Dr. William T. Blanford (1833-1905), died in London, having worked for the Geological Survey of India from 1855 until his retirement in 1882. In addition to numerous publications on the birds of India, he also published widely on mammals, mollusks, and arthropods of that region.
The deaths of five Corresponding Fellows were also reported. Sir Walter Lawry Buller (1838-1906) died in England, but he had spent most on his life in his native New Zealand. Although a lawyer by trade, he was long recognized as the leading authority on New Zealand. ornithology. Paul Leverkühn (1866-1905) died suddenly from pneumonia in Bulgaria, where he was Private Secretary to his Royal Highness the Prince of Bulgaria, and Director of his Scientific Institutions and Library. Emile Oustalet (1844-1905) was Chair of Mammalogy and Ornithology at the Paris Museum of Natural History at the time of his death. He was generally considered the authority on the birds of China and was President of the 3rd International Ornithological Congress, which was held in Paris in 1900. Victor Fatio (1838-1906), who died in Geneva, was considered the authority on the vertebrate fauna of Switzerland. The Reverend Henry Tristram (1822-1906) was the Canon of Durham (England), but he had traveled widely and was considered the authority on the birds of the Palestine region. He was a prolific collector: one collection of 20,000 skins was donated to the Free Museums of Liverpool in 1896, a large egg collection eventually was given to the British Museum of Natural History in 1901, and a second collection of 6,000 specimens was purchased near the time of his death by the Academy of Natural Sciences in Philadelphia.
The 24th congress was called to order by President Batchelder at the Business Meeting on Monday night, 12 November 1906, at The Portner, the largest apartment complex in Washington at the time, built by brewer and entrepreneur Robert Portner (1837-1906). Twenty-two Fellows were in attendance. Batchelder was re-elected President and Nelson and Chapman Vice-Presidents; Sage was re-elected Secretary and Dwight Treasurer; and Ruthven Deane, A. K. Fisher, Thomas S. Roberts, Witmer Stone, William Dutcher, Charles W. Richmond, and F. A. Lucas were re-elected members of the Council. The report of the Treasurer showed the finances of the Union to be in a satisfactory condition.
Waldron DeWitt Miller and Arthur T. Wayne were elected to the class of Member and 84 persons were elected Associates. One of those Associates was Stanley G. Jewett (1885–1955), who would go on to co-author the Birds of Oregon and the Birds of Washington State and become a Fellow in 1940. No Fellows were elected in 1906, but William Lutley Sclater (1863-1944) of Colorado Springs was named a Corresponding Fellow. The eldest son of the famous Phillip Lutley Sclater (1829-1913), who was the first editor of The Ibis and an original Honorary Fellow in the AOU, William spent only three years (1906-1909) as Director of the Colorado College Museum, but he managed to publish A History of the Birds of Colorado in 1912. Before that, he was the first Director of the South African Museum in Cape Town and Deputy Superintendent of the Indian Museum in Calcutta. From 1909 until 1944, when he was killed in a bombing attack on London, he was associated with the British Museum of Natural History. Like his father, he was editor of The Ibis (from 1913 to 1930) and eventually an Honorary Fellow in the AOU. He also was editor of Zoological Record from 1921 to 1938, served as President of the British Ornithologists’ Union from 1928 to 1933, and was Chair of their List Committee from 1928 until his death.
Changes to the by-laws were also adopted during the business meeting. The number of Members was increased from 75 to 100, and it was decided that Members and Fellows must be nominated in writing by three Fellows.
The following morning, the first day of the meeting was called to order by President Batchelder at the U.S. National Museum. Morning presentations included “A plea for the Killdeer“ and “Where wild birds sleep.“ The only afternoon presentation was “The home life of the California Condor.“ Dinner that night was at the Riggs House, followed by a reception at the hotel.
The second and third days of the meeting were called to order by Vice-President Nelson. Presentations on the second day included “Life zones of New York state as determined by its avifauna,“ “The habitats of a young California Condor,“ “A review of the genus Junco,“ and “On horseback through the deserts of Lower California.“ Two talks were given on the third day on the nesting biology of Bachman’s Warbler, one from Kentucky and one from South Carolina (Vermivora bachmanii). Resolutions were made thanking the Smithsonian Institution and the Audubon Society of the Distinct of Columbia for their hospitality during the meeting. It was agreed that the next meeting of the AOU would occur in Philadelphia in December 1907.