We are having the same problem with our flock (who are all adopted). Young drake seems to attack the 2 that have stopped laying (older). First he pulled at the eyes of one of them when she stopped laying and pulled a lot of feathers from her neck area and stomped on her when mating. Brought her to vet and kept her inside to recuperate. Now another has stopped laying and he is aggressive to her to the point I think he's hurt her lungs because she's wheezing while breathing. Taking her to vet tomorrow. Thank you for the advice of "Duck Jail" for drakes until Autumn. (I thought it was just Ricky because he's so young and was being a jerk.)