The cockatiel (''Nymphicus hollandicus''), also known as the quarrion and the weiro, is a member of the cockatoo family endemic to Australia. They are prized as household pets and companion parrots throughout the world and are relatively easy to breed. As a caged bird, cockatiels are second in popularity only to the budgerigar.
The cockatiel is the only member of the genus ''Nymphicus''. It was previously considered a crested parrot or small cockatoo; however, more recent molecular studies have assigned it to its own subfamily, ''Nymphicinae''. It is, therefore, now classified as the smallest of the Cacatuidae (cockatoo family). Cockatiels are native to Australia, and favour the Australian wetlands, scrublands, and bush lands.
== Taxonomy and etymology ==
Originally described by Scottish writer and naturalist Robert Kerr in 1793 as ''Psittacus hollandicus'', the cockatiel (or cockateel) was moved to its own genus, ''Nymphicus'', by Wagler in 1832. Its genus name reflects the experience of one of the earliest groups of Europeans to see the birds in their native habitat; the travellers thought the birds were so beautiful that they named them after mythical nymphs. The specific name ''hollandicus'' refers to New Holland, a historic name for Australia.
Its biological relationship had long been argued; it is now classified into a monotypic subfamily Nymphicinae but had sometimes in the past been misclassified among the Platycercinae, the broad-tailed parrots. This issue has now been settled with molecular studies. A 1984 study of protein allozymes signalled its closer relationship to cockatoos than to parrots, and Mitochondrial 12S rRNA sequence data〔Brown, D.M. & Toft, C.A. (1999): (Molecular systematics and biogeography of the cockatoos (Psittaciformes: ''Cacatuidae'') ). Auk 116(1): 141-157. 〕 places it amongst the Calyptorhynchinae (dark cockatoos) subfamily. The unique, parakeet (meaning long-tailed parrot) morphological feature is a consequence of the decrease in size and accompanying change of ecological niche.
Sequence analysis of intron 7 of the nuclear ''?''-fibrinogen gene, on the other hand, indicates that it may yet be distinct enough as to warrant recognition of the Nymphicinae rather than inclusion of the genus in the Calyptorhynchinae.〔Astuti, Dwi (2004): (A phylogeny of Cockatoos (Aves: Psittaciformes) inferred from DNA sequences of the seventh intron of Nuclear ?-fibrinogen gene ). Doctoral work, Graduate School of Environmental Earth Science, Hokkaido University, Japan.〕
The cockatiel is now biologically classified as a genuine member of Cacatuidae on account of sharing all of the cockatoo family's biological features, namely, the erectile crest, a gallbladder, powder down, suppressed cloudy-layer (which precludes the display of blue and green structural colours), and facial feathers covering the sides of the beak, all of which are rarely found outside the Cacatuidae family.
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