I have a lavender Orpington that she is just old enough to start laying eggs. She’s at her fifth egg that she’s laid so far I see that the rooster is mounting her, but I don’t know if the eggs are fertilized because she will lay the egg but will not sit on them. I have three in the incubator. That shows no signs of being fertilized. They’ve been in there about three days now I’ll keep them in there for a few more days, but I just put another one in there. How do I know for sure if they’re fertilized?