I have 3 female mallards and 1 Pekin that I'm 99.9% certain is female. One or more of my Mallards is laying eggs (they're all 4 months old). They are not sitting on them. I just find them in the coop they share with our 5 chickens in the morning. I'm assuming they are not fertile but they do fly around and we've seen some wild males "checking" our girls out. Questions: Why aren't they sitting/nesting on/with the eggs? Is there a way to tell if they are fertile? I dropped one this morning and it looked like a normal egg yolk/white. Aren't they a bit young to start laying?