I have heard stories and have actually seen where deer will be in a woods and be just as skitish as any other deer. But when a tractor or combine will come out into the feild to work land or something, the deer come out of the woods and graze. calmly. they have come accustom to the farm machinery. I have also heard stories that the owner of the peice of land i use to hunt would drive out to the woods in his tractor, sit there and let it run. and the deer would come out and come right up to the tractor. The same deer everytime. year after year.