A
frontal shield, also known as a
facial shield or
frontal plate, is a feature of the anatomy of several bird species. It consists of a hard or fleshy plate of specialised skin extending from the base of the
upper bill over the
forehead. The size, shape and colour may exhibit
testosterone-dependent variation in either sex during the year. Functionality appears to relate to protection of the face while feeding in, or moving through, dense vegetation, as well as to
courtship display and
territorial defence. It is a characteristic of some
water birds in the
rail family, especially the
gallinules and moorhens,
swamphens and
coots, as well as in the
Jacana family. The
watercock's frontal shield is extended above the head into a horn-like protuberance. A bird from a different order, the extinct
Choiseul pigeon, had a blue frontal shield.