Frontal shield

Common gallinule in Brazil

A frontal shield, also known as a facial shield or frontal plate, is a feature of the anatomy of several bird species. Located just above the upper mandible, and protruding along the forehead, it is composed of two main parts: a hard, proteinaceous callus and a soft, fleshy corium. It is thought to play roles in protection, mate identification, sexual selection, and territorial defense.