Thanks for the info everyone! Came here to ask this question and the answer was here. I have a leucistic (lack of pigmentation but not albino) Black Swedish duck (so she looks like a Pekin) and a Khaki Campbell drake. She is 24 weeks and has just begun laying with 6 eggs in 6 days. I knew to wait a few weeks, but wasn't sure if it was about egg size. I have indoor brooding area, so temp isn't an issue. (Mess might be - ha ha) I am very curious to see if she is fertile. We had a local leucistic mallard around for many years, and we never saw her with a brood, but nearly always with a drake. Not sure why, unless the genetic defect affects fertility too. Anyway, thanks for this great source of info and sharing!