Green’s Dictionary of Slang

1. (US) a professional singer.

1882

Nat. Police Gaz. (NY) 3 June 2/3: Patti, Gerster, Nilsson and the other highpriced squawkers are coming over the sea.

2. (US) one who makes a complaint, esp. a victim of crime.

1920		Capt. Billy’s Whiz Bang Oct. 6: Rebadow is neither soldier nor gambler but a dyed-in-the-wool squawker.
1927		D. Runyon ‘A Chilly Looking Blond’ in Brookhouser These Were Our Years (1959) 211: Old Father Adam, the original, and perhaps the loudest ‘squawker’ among mankind against women.
1929		Hostetter & Beesley It’s a Racket! 239: squawker—One who makes a complaint.
1931		Irwin Amer. Tramp and Und. Sl. 180: Squawker.–A dissatisfied customer, or one who, having been defrauded, makes a ‘squawk’ or complaint, either to the person responsible for the fraud or to the police.
1934		G. & S. Lorimer Stag Line 164: That dame looks like a squawker to me.
1942		S.F. Examiner (CA) 12 July 38/1: Loudest of the squawkers turned out to be [...] one Joe ‘Square Apple’ Lynch of Los Angeles.
1962		Ragen & Finston World’s Toughest Prison 819: squawker – A dissatisfied customer; or one who, having been defrauded makes a ‘squawk’ or complaint.

3. an informer.

1923		H.C. Witwer Fighting Blood 301: I am no squawker.
1931		W.N. Burns One-Way Ride 173: ‘I am no squawker,’ said Capone.
1940		W.R. Burnett High Sierra in Four Novels (1984) 329: She’s no loud-mouthed squawker.

4. (US teen) a parent.

1957

Shake, Rattle and Rock [film script] Must be a lot of our squawkers could give a finger.

5. (US teen) a record-player.

1958

H. Ellison Web of the City (1983) 80: Fish [...] yelled at Poop, ‘Shut off that squawker!’ Poop slammed the tone arm of the record player aside.

6. (Aus.) a chicken.

2015

N. Cummins Tales of the Honey Badger [ebook] I was working up the chook pen and thought ‘maybe we whack a few of these squawkers on the island’.