I've had deer carry on grazing quite undisturbed whilst I've been zeroing. I've also now (on 3 separate occasions) shot one deer, been in the process of gralloching, and had another deer appear. On two occasions I took the opportunity to shoot the second deer as well......
I agree with Tahr, in that I don't think deer necessarily associate the rifle shot itself with danger - that's why I always keep still/hidden when shooting one deer in a group, as I'd rather they don't link the shot with human activity. Earlier this season I shot a roe buck that was in a family group. The doe and two yearlings hung around for 15 minutes before wandering off. They didn't seem perturbed either by the shot or by the fact that the buck fell over! This only holds true, in my experience, if the shot deer drops to the shot. If the shot deer runs, then expect the other deer to scatter.
Where I zero there's regularly a group of beasts along the hill behind, about 400m away...they dont even lift their heads up! It's people they don't like, the shot, I reckon, is too far beyond their comprehension. Similar with cars, they just don't get it.
I shot a roe buck this season and before it was taken we were watching a fallow doe and her pricket which was no more than 30 yards or so from the roe. the fallow moved off and the shot was taken. Then the fallow came running in right up to the downed buck.
See the pictures under the article section------Herefordshire Roe Buck