Sicklebill & Riflebird Nonvocal Sounds
To add to their voices, some birds make nonvocal sounds as a form of communication. A familiar example is the drumming of woodpeckers, which takes the place of a song. Sicklebills and riflebirds make knocking and rustling sounds with their wings, and there are hints that the shapes they adopt as they display may help funnel these sounds toward females, like a megaphone.