I have watched deer around my place and how they react to the dogs barking, even when the dogs are outside and less than 50 yards from the deer. The deer go about their business as usual, occasionally looking up at the dogs, but then going back to feeding. Apparently, since the dogs are staying in place, not getting closer, the deer are comfortable, but do keep tabs on the dogs. While mowing, I've had deer within 25 feet and they just watched me. They're used to farm equipment, so the noise doesn't seem to bother them.