We have 1 Rouen drake, Victor, who is about a year old. We have a Mallard hen and a Rouen hen who are 8 months old and 2 Mallard hens who are 2 weeks younger. The hens are all laying huge beautiful eggs every day...the Rouen eggs are enormous! We eat them and I always check for fertile eggs. So far, none of the Mallard eggs have been fertile, but the Rouen eggs have been on occasion. So is my Mr. Big shooting blanks or what?????