yardbird

[yahrd-burd] /ˈyɑrdˌbɜrd/
noun, Slang.
1.
a convict or prisoner.
2.
an army recruit.
3.
a soldier confined to camp and assigned to cleaning the grounds or other menial tasks as punishment for violation of the rules.
Origin
1940-45, Americanism; yard2 + bird, by analogy with jailbird
British Dictionary definitions for yardbird

yardbird

/ˈjɑːdˌbɜːd/
noun
1.
(US, military) an inexperienced, untrained, or clumsy soldier, esp one employed on menial duties
Word Origin and History for yardbird
n.

"convict," 1956, from yard (n.1) + bird (n.1), from the notion of prison yards; earlier it meant "basic trainee" (World War II armed forces slang).

Slang definitions & phrases for yardbird

yardbird

noun
  1. A convict (1956+)
  2. A recruit; a asi trainee (WWII armed forces)
  3. A soldier who because of ineptitude or misdemeanor is confined to a certain area, and often ordered to keep it clean and neat (WWII armed forces)

[fr the fact that convicts exercise in the yard of the prison, and that neophyte soldiers are confined to the grounds of the training post during their first weeks; the basic metaphor is probably based on the behavior of urban pigeons]