Webster’s Revised Unabridged Dictionary · 1913
Flag
Flag, n. (Zoöl.) One of the wing feathers next the body of a bird; — called also flag feather.
Flag, v. t. To decoy (game) by waving a flag, handkerchief, or the like to arouse the animal's curiosity.
The antelope are getting continually shyer and more difficult to flag. T. Roosevelt.