JoeRE

I generally bleat with my mouth as I rarely have deer stop exactly where I would want them to. I think the key is to start softly so not to alarm the deer, then if that is not working, loudly. If I see no reaction then, I whistle. You can also generally tell by the body posture/what it is doing if the deer will likely be easy to stop. I have had to yell to stop a buck once even. I agree, you want to avoid getting a deer keyed up before the shot.