I'm experiencing the same thing with my drake, who is harassing my runner duck. He was difficult from the beginning, but seemed to mellow a bit after a rough adjustment period. Now he is back to his old antics. He chases my runner away from her food. If I give her a separate bowl of food on the other side of the yard, he chases her away from that too. I am currently separating him from my other 3 females, with periodic visits from the 2 females he gets along with. None of us are too happy about the new arrangement. I would like to re-home him, but there are not too many folks out there who are dying to get their hands on a drake. I really love the duck he is harassing, so I'd rather not re-home her. I also am not terribly fond of the drake. Right now I'd like to just wring his neck.