The collection consists entirely of photocopies of handwritten letters. The first letter, dated May 17, 1883, is from Albert S. Bickmore, founder and superintendent of the AMNH, concerning Mearns's proposed donation of a collection of birds. The second letter is from curator J.A. Allen, discussing details of the specimens. Other correspondents include James P. Chapin, Frank M. Chapman, L.P. Gratacap, C. Hart Merriam, Jenness Richardson and Anthony Woodward.