Grinnell had extensive contact with the terrain, animals and Native Americans of the northern plains, starting with being part of the last great hunt of the Pawnee in 1872. He spent many years studying the natural history of the region. As a graduate student, he accompanied Lieutenant Colonel George Armstrong Custer’s 1874 Black Hills expedition as a naturalist. He declined a similar appointment to the ill-fated 1876 Little Big Horn expedition. (Punke, p. 109)
In 1875, Colonel William Ludlow, who had been part of Custer's gold exploration effort, invited Grinnell to serve as naturalist and mineralogist on an expedition to Montana and the newly established Yellowstone Park. Grinnell prepared an attachment to the expedition's report, in which he documented the poaching of buffalo, deer, elk and antelope for hides. "It is estimated that during the winter of 1874-1875, not less than 3,000 Buffalo and mule deer suffer even more severely than the elk, and the antelope nearly as much." (Punke, pp. 102) His experience in Yellowstone led Grinnell to write the first of many magazine articles dealing with conservation, the protection of the buffalo, and the American West.
The Salamander Glacier and Lake Josephine, Glacier National Park. The Salamander used to be part of Grinnell Glacier but was named in the mid-20th century after Grinnell dwindled and split in two. Lying immediately beneath the Salamander, Grinnell Glacier is not visible in this photograph.
Grinnell made hunting trips to the St. Mary Lakes region of Glacier in 1885, 1887 and 1891 in the company of James Willard Schultz, the first professional guide in the region. During the 1885 visit, Grinnell and Schultz while traveling up the Swiftcurrent valley observed the glacier that now bears his name. Along with Schultz, Grinnell participated in the naming of many features in the Glacier region. He was later influential in establishing Glacier National Park in 1910. He was also a member of the Edward Henry Harrimanexpedition of 1899, a two-month survey of the Alaskan coast by an elite group of scientists and artists.
Grinnell was prominent in movements to preserve wildlife and conservation in the American West. For many years, he published articles and lobbied for congressional support for the endangered American buffalo. In 1887, Grinnell was a founding member, with Theodore Roosevelt, of the Boone and Crockett Club, dedicated to the restoration of America's wildlands. Other founding members included General William Tecumseh Sherman and Gifford Pinchot. Grinnell and Roosevelt published the Club's first book in 1895. Grinnell also organized the first Audubon Society and was an organizer of the New York Zoological Society.
With the passage of the 1894 National Park Protective Act, the remaining 200 wild buffalo in Yellowstone National Park received a measure of protection. It was nearly too late for the species. Poaching continued to reduce the animal's population, which reached its lowest number of 23 in 1902. (Punke, pp. 218–219) Grinnell's actions led to ongoing efforts by the Department of Interior to find additional animals in the wild and to manage herds to supplement the Yellowstone herd. This ultimately led to a genetically pure viable herd, and the survival of the species.
Grinnell’s books and publications reflect his lifelong study of the northern American plains and the Plains tribes. Along with J. A. Allen and William T. Hornaday, Grinnell was a historian of the buffalo and their relationship to Plains tribal culture. In When Buffalo Ran (1920), he describes hunting and working buffalo from a buffalo horse.
Grinnell’s best-known works are on the Cheyenne, including The Fighting Cheyennes (1915), and a two-volume work, The Cheyenne Indians: Their History and Lifeways (1923). His principal informant for both books was George Bent. George E. Hyde who may have done much of the writing. In 1928, Grinnell portrayed the story of Frank North and Luther North in Two Great Scouts and Their Pawnee Battalion. In other works on the Plains culture area, he focused on the Pawnee and Blackfeet people: Pawnee Hero Stories (1889), Blackfoot Lodge Tales (1892), and The Story of the Indian (1895).
Hunting on Three Continents, by George Bird Grinnell, Kermit Roosevelt, W. Redmond Cross, and Prentiss N. Gray (editors). New York: The Derrydale Press (1933) -- The seventh book of the Boone and Crockett Club, this wide-ranging collection includes accounts of Expeditions toward the North Pole and to the south of the Equator, articles relating to wild animals, and other pieces that speak the perils of hunting game to the brink of extinction. Among the most noteworthy contributions are "The Vanished Game of Yesterday" by Madison Grant, "An Epic of the Polar Air Lanes" by Lincoln Ellsworth, "Aeluropus Melanoleucus" by Kermit Roosevelt, "Taps for the Great Selous" by Frederick R. Burnham, "Volcano Sheep" by G.D. Pope, "Three Days on the Stikine River" by Emory W. Clark, and "Giant Sable Antelope" by Charles P. Curtis.
The Boy Scout's Book of True Adventure, Fourteen Honorary Scouts, with Foreword by Theodore Roosevelt and Biographical Notes By James E. West. Published by G. P. Putnam's Sons, New York (1931) -- Essays include: "A Tobacco Trade" by George Bird Grinnell, "Scouting Against the Apache" by Frederick R. Burnham, "How I Learned to Fly" by Orville Wright, "Adventurous Hunting" by Kermit Roosevelt, "An Arctic Mirage" by Donald B. MacMillan, "The First Crossing of the Polar Sea" by Lincoln Ellsworth, "In the Arctic" by Lincoln Ellsworth, "The Black Ghosts of the Tana River" by James L. Clark, "My Flight Over the Atlantic" by Richard E. Byrd, "In the Jungles of Cochin-China" by Theodore Roosevelt, "Shipwreck" by Robert A. Bartlett, "Written in the Air" by Charles A. Lindbergh, "Tiger! Tiger!" by Merian C. Cooper, "Bandits" by Clifford H. Pope, and "Adventure" by Stewart Edward White. All 13 photo plates of the honorary Scouts are present; both Roosevelts in the same photo.
^Langford, Nathaniel Pitt (1905). Diary of the Washburn Expedition to the Yellowstone and Firehole Rivers in 1870.
^Hanna, Warren L. (1986). "Exploring With Grinnell". The Life and Times of James Willard Schultz (Apikuni). Norman, Oklahoma: University of Oklahoma Press. pp. 133–145. ISBN0-8061-1985-3.
^Halaas, David Fridtjof and Masich, Andrew E. Halfbreed: The Remarkable True Story Of George Bent, Cambridge, MA: Da Capo Press, 2005, p. 344