You may need to take ownership of the yard as you have done in the house. This is all normal dog behavior when they feel there isn't a leader.
Also, my two sound similar to yours and the situation only it was all the time especially once Banks (girl) became older like 2 or 3.... she just wanted to rule everything. We had to keep them on seperate levels of the house if we were not at home. She attacked or tried to mount ALL the time and after many training sessions with a professional, we realized and accepted it was just her personality and we have to keep her in check and make sure she did not have the option to do any of the behavior.