Dead 4-week-old chicks in the nest

[giantshark18]

The one hen's behaviors is almost certainly because she is grieving the loss of the chicks, and I agree with you that the hen currently sitting on eggs most likely killed the chicks.

Thanks. My children keep asking what we can do for her and I am thinking we just give her her space to grieve.

 

[TaylorGlade]

Yes, she is probably grieving. I'm no chicken expert, but we just had to give away 9 of our 12 birds because they turned out to be boys. The girls have been unusually quiet. They seem otherwise fine. The only thing I can chalk it up to is they miss their flock mates. My grandmother used to have a separate spot for hens that were sitting because hens killing other chicks is a thing - and so will roosters.

 

[Allsfairinloveandbugs]

I don't think there's much you can do, although if your children want to spend extra time with her, talking to her and maybe offering a few special treats it surely won't hurt. Here is a very interesting article on the subject of grieving birds.
https://www.backyardchickens.com/articles/do-poultry-mourn-over-the-loss-of-a-flock-mate.67429/

 

[SourRoses]

For the future... sharing a nest between broodys and moms is not a good idea. Sometimes it might work out, but a broody on eggs has a high level of defensive hormones and stresses out easily. She probably thought the wriggling chicks were vermin after her eggs. At 3 weeks they're too big for trying to be under their own mom anyway, this is when she would naturally start insisting they give her room to breathe.

My own rule is just one broody at a time, any other volunteers get broken by moving them to the roost when it's too dark for her to jump down. A night of cool air under her is enough to break the urge (temperature and hormones are linked). If you catch it the first day it's easy.