At the Beinecke Rare Book and Manuscript Library is the Morris Tyler family collection of John James Audubon. They were descendants of his. See http://hdl.handle.net/10079/fa/beinecke.aud for a description of the collection. This collection spans 19 boxes of materials.

Also at the Beinecke Library is the John James Audubon collection consisting of 2 boxes of materials including letters signed and written by John James Audubon to his wife and colleagues. See http://hdl.handle.net/10079/fa/beinecke.audj for a description. 

Ornithological Notebook and Diary, 1860-1866, by Henry Seebohm with its feather specimens location