The crow thing is an old wifes tale, usually when the crows are making a stink it is because there is an owl around. Squirrels can help you or hurt you, if they start barking at you before there are deer in your area it will make the deer very alert looking for what they are barking at, but as already stated they will announce deer as they are coming in. Tree rats can be annoying at times, but for the most part they are fun to watch. I have very limited experience with turkeys and deer so I won' t comment on that one, and the only thing I can say from experience with fox and deer is one time I had a fox passing my stand I did a doe bleat and the fox took off like a scalded dog, so I would assume that deer will run foxes off.