The crest is a prominent feature exhibited by several bird species on their heads. It is distinct from features such as casques and cockscombs - sometimes erroneously referred to as "crests", which are bony and fleshy structures respectively.
The crest is made up of semiplume feathers: a long rachis with barbs on either side. These are plumulaceous feathers, meaning that they are soft and bendable. In birds, these semiplumes are common along the head, neck, and upper back, and may be used for buoyancy and sensing vibrations.