I have 2 females and one drake that are a mix of welsh harlequins and khaki's and are about a year old. They are all so sweet but recently my drake has been targeting one of my females and chasing her down. She will try to get away and it breaks my heart. He will grab her neck and mate with her more aggressively than the other and he only mates with the other in water. There is a bald spot on the back of her neck and I’m not sure what to do.