I have 3 or 4 hens hatch every year and have never had a hen reject a bad egg and kick it out of a nest, and I’ve had bad eggs. Others on here say they’ve seen it. You are dealing with living animals so I will not say it cannot happen just because I haven’t seen it. I do wonder if occasionally it’s an egg accidentally getting scratched out, whether it’s bad or not. To argue with myself, some people say they’ve put the egg back in and the same egg winds up back upon the coop floor.
I always mark and start all my eggs at the same time so they will hatch about the same time. After internal pip, after they have started breathing the air in the air cell, they do start talking to Mama. That lets the hen know one is still on the way. I’ve had hens take their chicks off the nest within 24 hours of the first one hatching, I’ve had broodies wait three days to bring them off. I always check the unhatched eggs and have not found any still alive after she left. That’s one of the reasons I let Mama decide when she wants to abandon the nest, she knows when the hatch is over. When I use an incubator I often get a response just from tapping on the top when one has internal pipped.
I don’t know how long your hen was off the nest or how cold it was while she was off. I don’t know how long those eggs have been incubated, the more developed they are the more internal heat the living chick inside generates. There are a lot of variables here. But I’ve had a broody hen go back to the wrong nest, I assume another hen was laying an egg in her nest when she returned from her daily sabbatical and she got confused. Anyway, those eggs were ice cold and were right around two weeks into incubation. I put her back on her eggs and about a week later she hatched 11 out of 11 eggs.
I’d trust your candling a lot more than the broody hen to tell if the eggs are still alive. But don’t do anything dramatic until you are sure. I suggest you candle at least twice a few days apart to see if you see any development.
Good luck!
