We had a hen who did this also. From the time the kittens were born, she would sit on them and keep them warm while the mother was out hunting, and then they'd trade places while the hen ate so the cat could feed her kittens.
I saw this photo of an Orpington Crele Legbar on a well-known auction site recently and just fell in love with it! The details stated that the seller was making 6 eggs from this award winning bird available for auction as a limited offer and may.
not pretty but functional chicken chunnel or tunnel from barn to free range areas to protect from predators. My worst predator is coyote, who hunts as soon as it begins to be grey - best thing is teach them to get inside before sunset