I have a Rouen (M) and Khaki Campbell (F) and they are about 6-8 months old. I just recently got a new duck who is a one year old female Indian Runner. The Khaki is mean to her! Both are female and yet, she beats up on the new duck! I fear for the new duck because she is smaller and won't defend herself. What is this behavior that is going on? Or are they "girl-fighting"? Did I introduce her to them wrong?