Birds produce different facial expressions by movements of the
beak, or by positioning the feathers above the beak, on the chin, or
atop the head. In some species, the feathers above the eye can also
move independently. Moreover, many species make a display by
opening their beaks. For example, the tawny frogmouth opens its
beak to reveal its large, bright green oral cavity, emphasizing the
size of its beak and making it appear more intimidating. Some oth-
er species open their beaks as a form of threatening behavior, usual-
ly silently, but sometimes enhance the performance with hissing or
loud breathing.
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Besides communicating by means of body language, birds
produce a great variety of sounds to communicate with oth-
er members of their flock, neighbors,
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