John James Audubon (1785-1851), the American Woodsman, is a legendary naturalist and bird artist. His technique of painting North American birds dramatically as they appeared in their natural habitat was a major contribution to the emerging discipline of ornithology in the nineteenth century. His masterpiece, The Birds of America (1827-1838), elephant folio, was followed by a companion text edition, Ornithological Biography (1831-1849), a smaller octavo edition of Birds (1840-1844) and The Viviparous Quadrupeds of North America, published posthumously. This collection of original letters of publication information, ornithology, and some personal notes was sent primarily to Lucy Bakewell Audubon, his wife, from 1826-1834, and to Victor Gifford Audubon, his son, from 1833-1834, 1840-1844, with some sporadic contact with both between 1836-1839. Items in the collection relate to Audubon's Florida, Great Egg Harbor, and Great Pine Forest expeditions but not to his final expedition up the Missouri River. Of particular note, letters of 1833 and 1834 contain references to his response to the Academy of Natural Sciences of Philadelphia president George Ord's attacks on his credibility. A partial journal entry from New Orleans in 1821 and a few letters to other correspondents, including John Bachman, round out the material.

These papers reflect Isaac Hays' interests and activities in the medical profession and as an editor. His interest in paleontology, especially in the controversy with G. W. Featherstonhaugh, is also represented. There is one separate volume (77 letters) containing correspondence about natural history and naturalists, written to Hays by C. L. Bonaparte, George Ord, Thomas Say, and Charles A. Lesueur. The correspondence in the larger collection, however, contains much material on the American Journal of the Medical Sciences, particularly illuminated in the correspondence with John D. Godman. The I. Minis Hays material consists of letters from doctors, relating to medicine and medical publications and editing, as well as medical organizations. Most significant of the correspondence is that with John Shaw Billings (ca. 60 letters).