Yes, they do scare some deer. I have several pictures of that. Some deer are curious and some seem to jump out of their skin....one buck...first picture he's sneeking, next picture he's standing on his hind legs leeping forward like he's going airborne.....I doubt however if it's enough to push them out. I have other shots of this same deer and saw him in the area during the season. Keep your human smell out of there and they'll accept that non threatening sound and flash.