'Game bird' definitions:

Definition of 'game bird'

noun

Any bird (as grouse or pheasant) that is hunted for sport

From: GCIDE

Game \Game\, a.
1. Having a resolute, unyielding spirit, like the gamecock; ready to fight to the last; plucky. [1913 Webster]
I was game . . . .I felt that I could have fought even to the death. --W. Irving. [1913 Webster]
2. Of or pertaining to such animals as are hunted for game, or to the act or practice of hunting. [1913 Webster]
Game bag, a sportsman's bag for carrying small game captured; also, the whole quantity of game taken.
Game bird, any bird commonly shot for food, esp. grouse, partridges, quails, pheasants, wild turkeys, and the shore or wading birds, such as plovers, snipe, woodcock, curlew, and sandpipers. The term is sometimes arbitrarily restricted to birds hunted by sportsmen, with dogs and guns.
Game egg, an egg producing a gamecock.
Game laws, laws regulating the seasons and manner of taking game for food or for sport.
Game preserver, a land owner who regulates the killing of game on his estate with a view to its increase. [Eng.]
To be game. (a) To show a brave, unyielding spirit. (b) To be victor in a game. [Colloq.]
To die game, to maintain a bold, unyielding spirit to the last; to die fighting. [1913 Webster]