We have mountain lions for our deer problem, although not enough. Admittedly, it does make parents nervous when a lion shows up at the middle school playground. Have seen deer kills at the local state park - which is at an old army fort and pretty urban. Don't know for sure it was lions...could have been coyote, I guess. When I moved into the new house, no fewer than 3 groups of people walking by said they hoped I wouldn't feed the deer like the previous owners.
Needless to say, any bonsai I care about is behind a 6' fence with a deer rail on top of that. They don't eat conifers, boxwood or pieris, if that helps. Everything I have is in pots - because I just moved in this summer so anything that does go into the ground is going to be fenced.