YIPES
JoeM is SOOOO right; you can call in bulls without any calls at all.
Bulls like to rub trees; and if you watch them do it; when they do it they make most trees move back and forth- producing a kind of swishing sound. You can of course; find a tree and push it back and forth; and bring in bulls.
You can rattle them in. Its a bit difficult to carry antlers in with you; risky in that when your camoed and walking with an elk rack... its dangerous.
But rattling does work. I have done it.
And danger though it is; when you have one coming into a rattle; holding the antler up so the bull can see it works well to.
Big problem is the weight and bulk while stalking.
You can also take a baseball bat size FRESH tree limb and smack a rub size tree with it; then drag it slowly up and down the tree; and then beat up dead branches on CLOSE trees ( as you might have an elk watching).
I have also called them in taking a branch and dragging it back and forth on the ground.
Theory to me is that when the bulls lose the velvet; they rub trees and get sap on them; and then rub the ground to darken their antlers. Just a theory - but I shot a bull doing just that once.
JoeM - a tip of the hat to you for mentioning it.