I went through a similar situation when my neighbors dumped Pekings in my pond and moved. We had to rescue them from the middle of the pond when it was frozen b4 preditors got them. We put a coop by the shoreline and fed them there. I witless whistle whenever I had food so they came every time. Once they realized they were safe in there coop at night, I had no problems. I would tell them to go to bed, they'd lay down and I'd let them out in the morning .