I don't think it affects them, if they're used to it. On a typical day in the woods I see anywhere from 2-20 deer. It's rare that I go out and don't see something. All the hunters in our woods, of 900 acres, use 4 wheelers. No recreational riding, just to and from the stand and dragging deer. We have 5 hunters and take 25-40 deer per season combined. I park about 150-200 yards from my stand and walk the rest of the way. A lot of hunters, especially ones not from suburban areas, don't realize that in these areas deer are not affected by a lot of noises and even some smells. I put corn out with my hands and have seen up to 14 deer on the same corn pile eating 2 hours later. Some people go deep into the woods, in suburban areas, and don't realize that the deer are on the edges where they know where the people are. I've taken 6 large 8 points in the last 6 years and countless does and they were all within sight or hearing of houses. Sometimes that little thicket between your house and the neighbors can hold bigger bucks than the center of a 500 acre piece of woods.