stupid egg question
I have a mallard and a drake. My hen has now had 19 eggs and how do I tell which are breakfast and which ones are ducklings? I mean yeah i know to candle them or use a strong light to see if there is a dark spot or for movement in the egg but, when does an egg have the embryo in there. should it apear to have a dark spot as soon as she lays it or a week after or when she starts to incubate them or what? The reason for my concern is that on Sunday we filled our manmade pond with water again and that's the first time since last fall. When we got done cleaning and filling it my mallard and drake went in the water and my drake instantly started pecking at her and jumping on her. well I was told that they mate in the water and that's how he fertilizes her. So now what I'm worried about is that if the 19 eggs that are already in her nest are just breakfast how would I be able to tell the fertilized eggs and the infertilized ones apart and what do I do with the ones that are the older ones? And she hasn't even incubated the eggs shes layed now. Does any of this make sense? Would be happy to hear anyones thoughts on this.