The person I gave the runner ducklings to that we hatched in the classroom was in today and asked me a question. He said his ducks were getting bare spots on the back of their neck. I told him it is because they have started mating. They were hatched in May of this year. He wasn't sure how many females or males he has. They have a nice little pond and then he brings them up to a pen near the house at night. I think I am right, but is there anything else that would cause that??? He is going to listen to voices and see if he can figure out how many are male and how many female.