The crest is a prominent feature exhibited by several bird and other dinosaur species [1] 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.
Crests on birds are generally used for display purposes. Cockatoos (a family that also includes corellas and the cockatiel) are part of the parrot family Cacatuidae found in Australia, the Bismarck Archipelago and the Philippines, and are probably the most recognizable birds to feature crests. [2] Cockatoos and cockatiels possess crests which may be raised or lowered at will. Their crests are used to communicate with fellow members of their species, or as a form of defense to frighten away other species that approach too closely, making the bird appear larger when the crest is suddenly and unexpectedly raised. [3] Crests can be recumbent or recursive, depending on the species. [4] The recumbent crest has feathers that are straight and lie down essentially flat on the head until the bird fans them out to where they stand up. The white cockatoo, for example, possesses a recumbent crest. [4] The recursive crest is noticeable even when it is not fanned out because it features feathers, that, when lying down, curve upward at the tips, and when standing up, often bend slightly forward toward the front of the head. Many recursive crests also feature brilliant colors. The sulphur-crested cockatoo has a recursive crest, and the Major Mitchell's cockatoo (also known as the Leadbeater's cockatoo) possesses a prominent recursive crest. [3] Some birds, like the galah, or rose-breasted cockatoo, have modified crests, which has features of both recumbent and recursive types. [3]
Many domesticated bird species have crest feathers. [5] These structures are known to have two origins: selective breeding or mutations. Crest feathers in domestic birds include a wide range of variations in form across species. The underlying molecular and genetic mechanisms that are responsible for crest feather formation in domesticated bird species are not well understood. As such, crest feathers are widely studied in morphological research and other related biological disciplines, particularly concerning domesticated species. [6]
A cockatoo is any of the 21 species of parrots belonging to the family Cacatuidae, the only family in the superfamily Cacatuoidea. Along with the Psittacoidea and the Strigopoidea, they make up the order Psittaciformes. The family has a mainly Australasian distribution, ranging from the Philippines and the eastern Indonesian islands of Wallacea to New Guinea, the Solomon Islands and Australia.
The Tanimbar corella, also known as Goffin's cockatoo or Tanimbar cockatoo, is a species of cockatoo endemic to forests of Yamdena, Larat and Selaru, all islands in the Tanimbar Islands archipelago in Indonesia. It has been introduced to the Kai Islands, Indonesia, Puerto Rico and Singapore. This species was only formally described in 2004, after it was discovered that the previous formal descriptions pertained to individuals of a different cockatoo species, the Ducorps' or Solomons cockatoo. Tanimbar corellas are the smallest of the white cockatoos. It is classified as Near Threatened due to deforestation and bird trade. It breeds well in captivity and there is a large avicultural population.
The cockatiel, also known as the weero/weiro or quarrion, is a medium-sized parrot that is a member of its own branch of the cockatoo family endemic to Australia. They are prized as household exotic bird pets and companion parrots throughout the world and are relatively easy to breed compared to other parrots. As a caged bird, cockatiels are second in popularity only to the budgerigar.
The pink cockatoo, also known as Major Mitchell's cockatoo or Leadbeater's cockatoo, is a medium-sized cockatoo that inhabits arid and semi-arid inland areas across Australia, with the exception of the north east.
The salmon-crested cockatoo, also known as the Moluccan cockatoo, is a cockatoo endemic to the Seram archipelago in eastern Indonesia. At a height of up to 46–52 centimetres (1.51–1.71 ft) and weight of up to 850 grams (1.87 lb), it is among the largest of the white cockatoos. The female is slightly smaller than the male on average. It has white-pink feathers with a definite peachy glow, a slight yellow on the underwing and underside of the tail feathers and a large retractable recumbent crest which it raises when threatened, revealing hitherto concealed bright red-orange plumes to frighten potential attackers. It may also be raised in excitement or in other 'emotional' displays. Some describe the crest as "flamingo-colored". It also has one of the louder calls in the parrot world and in captivity is a capable mimic.
The galah, less commonly known as the pink and grey cockatoo or rose-breasted cockatoo, is an Australian species of cockatoo and the only member of the genus Eolophus. The galah is adapted to a wide variety of modified and unmodified habitats and is one of Australia's most abundant and widespread bird species. The species is endemic to mainland Australia. It was introduced to Tasmania, where it is now widespread, in the mid-19th century and much more recently to New Zealand.
The white cockatoo, also known as the umbrella cockatoo, is a medium-sized all-white cockatoo endemic to tropical rainforest on islands of Indonesia. When surprised, it extends a large and striking head crest, which has a semicircular shape. The wings and tail have a pale yellow or lemon color which is exposed when they fly. It is similar to other species of white cockatoo such as yellow-crested cockatoo, sulphur-crested cockatoo, and salmon-crested cockatoo, all of which have yellow, orange or pink crest feathers instead of white.
The sulphur-crested cockatoo is a relatively large white cockatoo found in wooded habitats in Australia, New Guinea, and some of the islands of Indonesia. They can be locally very numerous, leading to them sometimes being considered pests. A highly intelligent bird, they are well known in aviculture, although they can be demanding pets.
The citron-crested cockatoo is a medium-sized cockatoo with an orange crest, dark grey beak, pale orange ear patches, and strong feet and claws. The underside of the larger wing and tail feathers have a pale yellow color. The eyelid color is a very light blue. Both sexes are similar. Females have a copper colored eye where as the male has a very dark black eye.
The Solomons corella, also known as Solomons cockatoo, Ducorps's cockatoo or broad-crested corella, is a species of cockatoo endemic to the Solomon Islands archipelago. This small white cockatoo is larger than the Tanimbar corella yet smaller than the umbrella cockatoo. The species is common across most of the Solomons, absent only from Makira in the south. It inhabits lowland rainforests, secondary forests, cleared areas and gardens.
The yellow-crested cockatoo also known as the lesser sulphur-crested cockatoo, is a medium-sized cockatoo with white plumage, bluish-white bare orbital skin, grey feet, a black bill, and a retractile yellow or orange crest. The sexes are similar.
The little corella, also known as the short-billed corella, bare-eyed cockatoo, blood-stained cockatoo, and little cockatoo is a white cockatoo native to Australia and southern New Guinea. It was known as Birdirra among the Yindjibarndi people of the central and western Pilbara. They would keep them as pets, or traditionally cook and eat them. The downy feathers are used in traditional ceremonies and dances where they adorn head and armbands.
The gang-gang cockatoo is a parrot found in the cooler and wetter forests and woodlands of Australia, particularly alpine bushland. It is the only species placed in the genus Callocephalon. Mostly mild grey in colour with some lighter scalloping, the male has a red head and crest, while the female has a small fluffy grey crest. It ranges throughout south-eastern Australia. The gang-gang cockatoo is the faunal emblem of the Australian Capital Territory. It is easily identified by its distinctive call, which is described as resembling a creaky gate, or the sound of a cork being pulled from a wine bottle.
The blue-eyed cockatoo is a large, mainly white cockatoo about 50 cm (20 in) long with a mobile crest, a black beak, and a light blue rim of featherless skin around each eye that gives this species its name.
Described by French naturalist Anselme Gaëtan Desmarest in 1826, the genus Calyptorhynchus has two species of cockatoos. They are all mostly black in colour, and the taxa may be differentiated partly by size and partly by small areas of red, grey, and yellow plumage, especially in the tail feathers. Studies based on the mitochondrial DNA 12S gene fragment suggested that other sexually dichromatic species, the gang-gang cockatoo and the cockatiel may be the closest living relatives of Calyptorhynchus. However, subsequent studies, including more genes confirm the morphological taxonomy with the gang-gang cockatoo most closely related to the galah, within the white cockatoo group, and with the cockatiel as a third distinct subfamily of cockatoos.
The Triton cockatoo is one of the four subspecies of the sulphur-crested cockatoo. The cockatoo was first described by Dutch zoologist, Coenraad Jacob Temminck, in 1849. There is no documentation as to why Temminck selected this name however it is suggested that it was named after the Dutch corvette, Triton, which operated off the Dutch New Guinea coastline, in 19th century.
The Mathews' cockatoo or northern sulphur-crested cockatoo is a subspecies of the sulphur-crested cockatoo. Its scientific name relates to the area in which it was first found, the Fitzroy River and its common name comes from Gregory Mathews, the Australian ornithologist who first identified it as a subspecies in 1912.