The helmetted hornbill (Rhinoplax vigil) is a bird that lives in the rainforests of South and Southeast Asia. It is distinguished by the bulky yellow "helmet" worn over its beak. This hollow helmet, a veritable sound box, serves to amplify the nasal noises it emits. This bird is extremely faithful. Once males and females have chosen each other, they live together for life. During the nesting season, the female settles into a tree hole and bricks up the entrance with mud, saliva and excrement, leaving only a small hole through which the male feeds her. This nest protects her from predators throughout the incubation period.