Broody hens Broodiness is a physiological state and maternal behavior exhibited by hens who want to be mothers. Their physiology and behavior will change in order to achieve this. What causes Broodiness? - when the release of a hormone called prolactin increases, it stops the production of gonadotropin, stopping ovarian follicle progression (the beginning of the egg production cycle), stopping the hen from laying. A broody hen will pluck the feathers from her underside so that her warm skin is i