My Cayugas ducklings are both losing their down but not getting feathers in place of it. They have white bald patches. Are they being picked on, or is this normal? I got a Khaki Campbell at the same time, same age, and she is twice the size of the Cayugas and never had bald spots. I have also raised Pekins and Mallards and they never went through a bald patch stage. They are about 6 weeks old.