Correspondence, primarily to George Burritt Sennett from fellow ornithologists, concerning bird taxonomy and conservation efforts. Major correspondents include William Brewster, Arthur P. Chadbourne, Frank M. Chapman, George Bird Grinnell, H. W. Henshaw, F. W. Langdon, G. H. Ragsdale, Robert Ridgway, who was curator of the Department of Birds, United States National Museum, and J. A. Singley.