Green’s Dictionary of Slang

1. (US) a rustic, a simpleton, a novice, a newcomer.

1886		Daily Eve. Bull. (Maysville, KY) 28 Dec. 2/1: The Jaybird who perches in that office poses as a newspaper expert.
1897		A.H. Lewis Wolfville 202: Whatever makes this yere Jaybird Bob believe he’s a humorist.
1905		Muskogee Cimeter (OK) 6 Apr. 1/3: It was a caution to see the Jaybird backstep and play the Craw-dad act.
1931		(con. 1918) E.W. Springs Rise and Fall of Carol Banks 176: There was no place a jaybird could make a safe landing.
1944		C. Himes ‘A Penny for Your Thoughts’ in Coll. Stories (1990) 62: If we get the jaybird, the rest of you make a break for the lines.
1964		W. Hill One of the Casualties 54: Sigmund is for the jaybirds....That head-candlin jazz is okay for well-heeled nuts that can afford twenty bucks an hour couch rent, maybe, but I got a sneaky suspicion nobody comes out ahead by the head-shrinker [HDAS].
1982		M. Braun Judas Tree (1983) 128: Who was the jaybird they hung?

2. an African-American.

1889		Fort Worth Gaz. (TX) 19 Aug. 1/3: The Jaybirds seem more determined than ever to control the government.
1912		Colfax Chron. (LA) 18 May 5/2: John Tinaglia, an Italian, had shot Harrison Gray, alias ‘Jaybird,’ and Napoleon Kees, both negroes.
1917		Mt Vernon Signal (KY) 30 Mar. 4/1: The Peckerwood-Jaybird War in Fort Bend County Texas [...] the two factions were called the Jay Birds [i.e. blacks] and Peckerwoods [i.e. whites].