I agree with you Chemist. I have noticed this before, and not just deer. Take crows for example. They put up one or two watch birds
around the field they are eating in. You can walk around the field with nothing and they will stay there. Pick up a stick and there they go. I used to practice stalking deer by sneeking up on crows in a field and shooting them with a rifle or pellet gun. Try it sometime, afterward, you will think deer are easy. I have also heard that if the crow on watch doesn't sound the alarm and a crow gets hurt that the other crows will kill him. Smart critters