On the game preserves where you buy the birds and they are set out in a field for you, do they do anything to the birds first before setting them on the ground? I thought the bird handlers did something so that they wouldn’t fly off, just stay tight until they were flushed. The birds in question are chukars.
i was taught a trick with quail that should work with chukars too. kneel down in the spot you want to plant the bird, wrap your entire hand around the birds body and leave his head and neck sticking out the top of your hand. hold the bird firmly and gently and spin it around like you were twirling a cain, or a steelers terrible towel, or like you were twirling a lasso, only in front of you instead of over your head. spin them about 8-10 times and stick them in the cover. do it all in one motion without a pause beween the spinning and the burying in cover.
the guy called it "dizzying" the bird and its worked for me. although i only use this for training dogs and have never tested it past about 45 minutes, but quail will stay put that long anyway