I have over eighty baby chicks right now and two hens setting on more eggs. The eighty chicks are split up into five broody hens. One hen on eggs has hers hatching and this morning she killed two before they hatched and a second ago i found one dead and another cheepping and it was very cold rolled to the side. I took the living chick away and put it with a hen that hatched chicks yesterday. Why is she killing her own chick?