The beak, bill or rostrum is an external anatomical structure of birds which, in addition to eating, is used for grooming, manipulating objects, killing prey, probing for food, courtship and feeding their young. The term also refers to a similar mouthpart in some cephalopods, cetaceans, turtles, Anuran tadpoles and sirens. Anatomy Beaks can vary significantly in size and shape from species to species. The beak is composed of an upper jaw called the maxilla, and a lower jaw cal… (More on Beak)