I've called them in from far away from a tree stand & it is amazing how they come right to the base of the tree looking for the elk. The way they pin point the sound location is awesome. I don't call when they are close or even move, I just let them mill around . I'm sure they would pick you off from the movement and also look up for the sound location. I would call to bring them in & then cut it off. Maybe get a Montana decoy to set up behind your tree setup ?