There seems to be several versions of "The Cuckoo Bird" or "Coo Coo Bird". The song is known by many names, including "The Coo-Coo", "The Coo-Coo Bird", "The Cuckoo Bird", "The Cuckoo Is A Pretty Bird", "The Evening Meeting", "The Unconstant Lover", "Bunclody" and "Going to Georgia".
Cecil Sharp collected fifteen variants in England and published one (the minor mode version) in One Hundred English Folksongs (1916). A few years later in his American travels he collected thirteen more in Kentucky, Virginia and North Carolina, all of which seem to be in major mode. He published these melodies (but not all of the lyrics) in English Folk-songs from the Southern Appalachians. Sharp points out similarities between the minor mode English version and the melody usually used for "High Germany". The American versions seem to fall into the widespread "Wagoner's Lad" family of songs. The melodies vary more than the lyrics which, particularly in Kentucky, often share lyrics with the most well-known of the "Wagoner's Lad" songs "On Top of Old Smokey". The most commonly known version today is Clarence "Tom" Ashley's version with banjo recorded by Columbia Records Nov. 23, 1929. Ashley seems to have developed his version independent of tradition and relied on the banjo to define his melody. His lyrics are not so much related to the English traditional variants as to black blues and other blues related songs (e.g.: "Wish I Was a Mole in the Ground"). He subsequently recorded with Doc Watson, Hobart Smith and The Carolina Tar Heels.
In the 1960's folk song revival it was recorded by Jack Elliot, Kelly Harrell, Doc Watson (solo), The New Lost City Ramblers, The Osborne Brothers, Mac Wiseman and Big Brother and the Holding Company. Its popularity may be due to Doc Watson's smooth performances.
I learned this first from The New Lost City Ramblers and later from the re-release of Ashley's recording in The Anthology of American Folk Music.