When I hunted my 200 acre farm in GA, I debated the ATV vs walking question off and on. I know that when I walked in the dark and spooked deer, they seem very disturbed, maybe because they could hear me but not quite make out what I was from time to time. Observing deer from a stand when an ATV was near by and passing I would watch to see how the deer react. They would lift their heads and turn their ears but as long as it continued, they did not seem to care. This is not what I'd call wilderness, mostly farm area. My overall opinion is that deer (in this case) are not as disturbed when they can hear something coming and going that does not catch them off guard, especially when they are around farm equipment. I theorize that they are less spooked when they hear an ATV vs the walking disturbance of something they can not identify in the dark.
