Green’s Dictionary of Slang

beaker n.2

[SE beak]

(UK Und.) a fowl, a chicken.

[UK]‘Ducange Anglicus’ Vulgar Tongue.

In compounds

beaker-hauler (n.)

a poultry thief, who hawks booty from door to door.

Probert Encyc. 🌐 Beaker-hauler is slang for a poultry thief who sells stolen poultry door-to-door.
beaker-hunter (n.) (also beak-hunter)

a poultry-thief; thus beak-hunting/beaker-hunting, poultry-stealing.

[UK]H. Brandon Dict. of the Flash or Cant Lang. 161/1: Beaker Hunter – poultry stealer.
[UK]J. Archbold Magistrate’s Assistant 445: A poultry stealer. A beaker-hunter.
[UK]Worcs. Chron. 3 Oct. 4/1: Poultry-stealer — beak-hunter.
[Aus] gloss. in Occurence Book of York River Lockup in Seal (1999) 37: He has been lagged for beaker hunting.
[UK]J. Greenwood Seven Curses of London 87: Poultry stealing – beak hunting.
[UK]Sl. Dict. 79: Beaker-hunter, or beak hunter a stealer of poultry.
[Aus]Sydney Sl. Dict. (2 edn) 1: Beaker Hunter - Poultry stealer.
[UK]Clarkson & Richardson Police! 321: Fowl-stealing ...Biped-gathering, beaker-hunting.
[Aus]Crowe Aus. Sl. Dict. 7: Beaker Hunters, fowl stealers.
[Aus]Argus (Melbourne) 20 Sept. 6/4: Among these small fry of the profession may be included the baster or house thief, the beaker-hunter, and the snagler, who are both on the roost lay, or poultry stealing.
[UK]J. Ware Passing Eng. of the Victorian Era.