How do chickens do it

[caseybloo]

I stole 13 eggs from her nest and left 1 in there. She layed 7 more and started setting. I got 7 out of 13 last Wednesday in my incubator (maybe some were old) and she got 8 for 8 yesterday. Amazing! Do you think a towel or small pillow on top of the eggs would be more like a chicken? Thinking out loud...how do they do it

? Would it be better to put the new ones in the box with the older ones or put the older ones with the hen and the new ones?

 

[chicks are me]

How old were the eggs that didn't hatch?