I have 4 call ducks. 3 males and 1 female. Recently 2 of the male ducks started chasing and nipping at the tail of the other male duck. They are not pulling the feathers out. Can anyone tell me why this is happening? It seems like this duck has been singled out of the group. He swims with the other ducks but far behind them, and often sleeps by himself outside the house, while the other 3 are together! I feel sad for him could it be the male to female ratio is off? Should I get more ducks to join them? Thanks!