He was appointed in 1880 by Spencer Fullerton Baird, secretary of the Smithsonian Institution, to be the first full-time curator of birds at the United States National Museum, a title he held until his death.

Ridgway was an outstanding descriptive taxonomist, capping his life work with The Birds of North and Middle America (eight volumes, 1901–1919).

[2] This interest to explore nature, both shooting with a gun given to him by his father, as well as drawing from life, was encouraged by his parents, his uncle William, and his aunt Fannie Gunn.

[5] The mentor and protégé continued their exchange of letters, which led to Ridgway's appointment, in the spring of 1867, as the naturalist on Clarence King's Survey of the 40th Parallel.

[8] In an undertaking that lasted nearly two years, Ridgway collected 1,522 bird-related specimens (753 nests and eggs and 769 skins) and served as a key member on one of the four great surveys of the American West.

Upon his return to Washington, Ridgway illustrated and wrote for Baird and Thomas M. Brewer's History of North American Birds project.

[16] Returning the favor that Baird had paid him, he responded to letters from the public to identify birds and provided artist's materials to a painter in California.

[19] Charles Wallace Richmond joined the institution in 1893 (at first, as a night watchman) and was soon tasked by Ridgway with writing reviews and other short pieces.

He provided calculations of the wing loading and other aerodynamic characteristics of species like the wandering albatross, turkey vulture, and other soaring birds.

[21] In 1883, Robert Ridgway was a founding member of the American Ornithologists' Union (AOU)[22] and he became an associate editor of the organization's journal The Auk.

[26][27] As scientific knowledge expanded quickly in the second half of the nineteenth century, the need for reorganizing the system of names used to describe North American birds grew commensurately.

[29] Ridgway and Coues, along with Joel Asaph Allen, William Brewster, and Henry W. Henshaw, came together as a committee on nomenclature and classification, serving the newly founded AOU, to reconcile the various systems and catalogs.

The Code settled the disagreement about capitalization of species names[30] and established today's order of presentation, with waterbirds first and passerines last.

[37] Ridgway was also honorary member of the Nuttall Ornithological Club of Cambridge, Massachusetts, for which he contributed illustrations and 48 articles to its Bulletin.

[39][40] Although he lacked formal post-secondary education, Ridgway received an honorary master's degree in science from Indiana University in 1884, as a sign of gratitude for his supplying them with bird specimens after their museum burned down.

"Audie" had begun a promising career in ornithology at the Field Museum of Natural History when his life was cut short by a fatal bout of pneumonia.

[48] In early June 1913, Robert Ridgway and his wife Julia ("Evvie") moved to Olney, Illinois, to reduce physical and mental stress so that he might complete The Birds of North and Middle America, of which five of eight parts had already appeared.

[49] They built a new house on 8 acres (3.2 hectares) that they had purchased in 1906, and named the place Larchmound for two large larch trees growing on the property.

[71] An advisory committee was formed, with scientific illustrator William Henry Holmes as chairman and Richard Rathbun (newly appointed assistant secretary) as one of its five members.

[75] In 1901, however, the tension between the committee's broad vision of commercial applications for the project and Ridgway's narrow objective of a naturalist's reference book ended the Ridgway-Smithsonian collaboration in the endeavor.

[77][78] The work became a standard reference used by ornithologists for decades after Ridgway's death, as well as specialists in such wide-ranging fields as mycology, philately, and food coloring.

[84] A significant proportion of Ridgway's output consisted of formal scientific descriptions of new forms of birds (new genera, species, and subspecies), many of them native to Central and South America.

[86] As subsequent research has revised the taxonomy of birds, not all of the forms that Ridgway described remain recognized as distinct, but his contributions are still substantial.

[87] While most of the forms described and named by Ridgway came from outside the United States, in one instance he identified a new taxon first collected no earlier than 1881, in the Catskill Mountains of New York, an area already well-explored by ornithologists.

[94] Continuing the pattern of the Manual (and Baird's earlier Review of American Birds), each volume featured an appendix of engraved outline drawings of generic characteristics.

[98] Spencer Fullerton Baird and his followers emphasized precision of description, traceability through the literature, the accumulation of empirical evidence (that is, numerous specimens), and deductions drawn from facts — in opposition to the so-called "European school" of the time, which depended on personal authority.

[100] However, as ornithology around the turn of the twentieth century began to focus on bird behavior, reproduction strategies, and other aspects of the living organism, Ridgway fell behind the advances made by his colleagues of the succeeding generations.

[105] In 1919, Ridgway was awarded the Daniel Giraud Elliot Medal from the National Academy of Sciences for his Birds of North and Middle America.

[108] In 1921, he was the first to receive the AOU's William Brewster Memorial Award, which recognizes "an exceptional body of work on birds of the Western Hemisphere.