About three weeks ago I purchased three Muscovy Ducks two hens and one drake. The first two weeks went by with no incident and they got along well. But this week he has completely switched personalities. He has been relentlessly chasing my other ducks and pulling out their feathers. He'll grab them and force them to the ground before just walking off. He doesn't try to mate with them he just forces them to the ground. Is there anything I can do to dial down his behavior?