[1][8] Despite initial resistance on the part of his parents, he entered Cornell University as a graduate student of ornithology, studying under Arthur A. Allen.

Griscom's master's thesis dealt with field identification of ducks of the eastern United States, and he received his A.M. degree from Cornell in 1915.

[11] In 1916, Griscom joined the staff of the American Museum of Natural History (AMNH) in New York, initially in the ichthyology department where he co-authored one paper on fishes with John Treadwell Nichols.

[1][18] During World War I, Griscom served as a 2nd Lieutenant (2LT) in the United States Army within the Psychological Subsection of Military Intelligence, part of the American Expeditionary Force (AEF) in France.

His duties included designing and distributing propaganda materials, such as leaflets delivered via hydrogen balloons, aimed at influencing German soldiers and civilians.

In a letter home, he described observing European bird species, including larks and warblers, which he marveled at as a welcome distraction from the chaos of war.

[29] He was elected treasurer in 1930 (succeeding Charles Foster Batchelder), was subsequently named a member of the council,[30] and served a term as president from 1952.

[32] As at the AOU, he emphasized identification of birds by field marks rather than in the hand, and the organization's meeting minutes expanded to accommodate his notes of recent sightings.

In a controversial move, Griscom organized the sale of a portion of the Society's books (many of which were duplicated within the Boston area), with much of the library going to the University of Southern California.

[1][42] He led an expedition to Panama in 1924; members of the party described fifteen new species of birds while he himself published descriptions of the yellow-green brushfinch and the Tacarcuna bush-tanager.

[1][43] In 1925, Griscom was part of a team led by Gregory Mason and Herbert Spinden that collected specimens for the AMNH in British Honduras, the Yucatan Peninsula, and Cozumel Island.

[1][45] Griscom named two new species as a result of the Guatemala trip, the flightless Atitlán grebe (now extinct) and (with Jonathan Dwight) the belted flycatcher.

The story is told that, as a young birder of about twenty, he impressed senior ornithologists by identifying a female Cape May warbler visually, this judgment later confirmed by shooting the bird.

[47] Whether or not the story of the warbler is entirely true, Griscom was indeed skilled at quickly identifying birds by sight, using diagnostic features first learned from his museum work,[48] and he influenced other birders and ornithologists to use the same techniques.

[58] But his particular passion was for Big Days, a friendly competition in which a team of birders traverses a region, intending to find and identify as many bird species as possible in a 24-hour period.

Working from a growing volume of sightings by skilled observers, Griscom provided in these books the details of exactly where a bird could be found in a region (for instance, a specific park or beach), at what time of year (in spring migration, for example), and in what numbers.

From 1907 until the end of his life, Griscom transcribed his field notes made during trips in the United States and overseas into a set of large ledger books.

[61] In the field, Griscom is remembered by friends and students for his virtuosity in identification, his enthusiasm and brusque sense of humor, and his great satisfaction in teaching others the pleasures of birding.

[64] Griscom tested Peterson's paintings for the book's publisher, Houghton Mifflin, demonstrating that the renderings provided the right details that could be used to identify birds in the field.

[66] During his New York years, Griscom became a teacher to a group known as the Bronx County Bird Club,[66] whose members included Peterson, Allan Cruickshank,[67] and Joseph J.

[72] From his position as an eminent ornithologist and officer of organizations like NAS, Griscom was an activist on behalf of conservation issues, especially those that affected coastal Massachusetts and the Atlantic flyway.

He emphasized habitat preservation (of both breeding and wintering ranges) and public education, so that conservationists, sportsmen, voters, and policymakers alike could make informed decisions; he followed a path of moderation and compromise.

[83] At Parker River National Wildlife Refuge, the "Dean of the Birdwatchers" is remembered by a bronze plaque mounted on a five-ton granite boulder near Hellcat Swamp.