Western rosella
Western rosella
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Western rosella

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Western rosella

The western rosella (Platycercus icterotis), or moyadong, is a species of parrot endemic to southwestern Australia. The head and underparts are bright red, and the back is mottled black; a yellow patch at the cheek distinguishes it from others of the genus Platycercus. Adults of the species exhibit sexual dimorphism with the females duller overall; juveniles lack the striking colours of mature birds and the characteristic patterning is not as easily distinguished. Their communication call is a softly delivered pink-pink sound, and much of their behaviour is comparatively unobtrusive. Their habitat is in eucalypt forests and woodlands, where they often remain unobserved until they appear to feed on seeds at nearby cleared areas.

Individuals form mating pairs and generally remain in one locality, although they will venture out to join small groups at plentiful sources of food. The western rosella is predominantly herbivorous, its diet consisting mostly of seeds of grasses and other plants, although nectar and insect larvae are sometimes eaten. The damage attributed to the species at introduced fruit and grain crops saw them declared as a pest and permitted by the state to be killed or captured. They are more placid and sociable than rosellas of other Australian regions from which they are geographically isolated and have become internationally popular as an aviary bird. Their history in aviculture begins with two 1830 lithographs of live specimens in England by Edward Lear. Successful breeding in captivity began there during the early 20th century.

The population is classified as two subspecies, representing an inland group residing in the agricultural district and another nearer the coast in kwongan, tall forest and a variety of woodlands. The abrupt intersection of these groups' range, delineated by country of lower rainfall between Albany and Geraldton, is a zone of hybridisation between the two subspecies Platycercus icterotis icterotis and P. icterotis xanthogenys. The classification of the species relationship to sister taxa of Platycercus is less complex, due to their ecological and geographic isolation, and they are allied to a subgenus Platycercus (Violania) .

The first description of the species was published by C. J. Temminck and Heinrich Kuhl in 1820 as Psittacus icterotis, using a collection obtained at King George Sound (Albany, Western Australia). Kuhl was once mistakenly given sole authorship for the description; this was later corrected to include Temminck; Kuhl himself cited Temminck's earlier work in the text describing their three specimens. The epithet icterotis, meaning 'yellow ear', is derived from ancient Greek and presumed to refer to the yellow cheek. They were separated from the genus Psittacus in 1830 by Nicholas Vigors, to the genus Platycercus he had erected five years earlier; the specific epithet he nominated was Platycercus stanleyii.

Two subspecies are recognised at the Australian Faunal Directory, the nominate Platycercus icterotis icterotis and a description of inland specimens as subspecies Platycercus icterotis xanthogenys. The inland subspecies cites Tommaso Salvadori's 1891 description of a new species Platycercus xanthogenys, published in the Proceedings of the Zoological Society, emerging from his work on a catalogue of psittacine specimens at the British Museum; the latter work contains an illustration of the holotype by J. G. Keulemans. A revision in 1955 by Arthur Cain proposed the type locality for P. icterotis xanthogenys was Wongan Hills, arbitrarily, but accepted as logical in assuming that John Gould's field worker, John Gilbert, could have obtained a specimen there and it resembled those found occurring at that location. A revision by Herbert Condon, published in the Checklist of the Birds of Australia (RAOU, 1975), supports a classification of two subspecies:

Revision and cataloguing in the 20th century began to examine the classification of the few known specimens, often supplied without location details, and, excepting A. J. North, cited the work of Savadori in 1891. In a review of material in the Tring collection in England, supplemented by Bernard Woodward at the Perth Museum and the collection of field worker J. T. Tunney, the trinomial Platycercus icterotis xanthogenys was published by Ernst Hartert in 1905. The author Gregory Mathews, an avid exponent of subspecific classification, cites the species Platycercus xanthogenys Salvadori, but disposed of the epithet xanthogenys when tentatively proposing three new taxa. Mathews notes Salvadori's separation of the type specimen from two others in the Gould collection, then held at the London museum, and caution in only giving the source of the skin as "unknown, but probably Australia". Mathews proposed three subspecies in 1912, each given a brief distinguishing remark to be expanded in a later volume of his series Birds of Australia.

The entry in that 1917 work addresses the type of nominate P. icterotis icterotis, which he had earlier ascribed to the location "Shark Bay". This was corrected by Mathews to the location "Albany, South-West Australia". In the preface to the same volume, Mathews attributes the material examined from the southwest of Australia to the collections of the botanist Robert Brown on the Flinders expedition. The author also corrected his reference to "Point Cloates", given in his 1912 determination of the unknown source of the type in Salvadori's 1891 description, Platycercus xanthogenys. He put the location beyond York, Western Australia. This is where John Gilbert was known to have collected when visiting the western colony in the 1830s. A new taxon P. icterotis salvadori (yellow-cheeked parrot) differentiates those found at Wilson's Inlet as "having less red on the mantle", and another, P. icterotis whitlocki (Dundas yellow-cheeked parrot), as smaller, less blue at the wing, and more subdued red feathers at the head in the specimens obtained from Lake Dundas (Dundas). The epithet whitlocki was used by authors in ornithological literature to honour the Western Australian field research of Frederick Lawson Whitlock. The notes of Whitlock and other authors reporting from Western Australia, including Tom Carter and A. W. Milligan, were assembled or quoted by Mathews. Errors introduced to the scant body of knowledge by himself and others were acknowledged. The variation in the colours of the back was proposed to accord with differing habitat or as a characteristic of fully mature plumage. He concluded there were at least two subspecies—approximating the coastal and inland forms—that may prove to be more diverse if a complete series of specimens was examined. The description of the population as two or three subspecific taxa by Mathews is cited within the species circumscription, his P. icterus whitlocki, along with Salvadori's P. xanthogenys, are noted as synonyms for the inland subspecies.

The platycercine parrots have seen various systematic arrangements to circumscribe the contentious sister taxa of northern and eastern Australia, most of which overlap in range and intergrade. One study resulted in new genera being published by Wells and Wellington in 1992. In their classification, the genus name Hesperapsittacus was described, and this species was proposed as the type. That revision was subsumed several years later, by Richard Schodde (1997), to subgeneric names; the name Hesperapsittacus became available for Schodde's subgenus, but he nominated their genus name Violania instead for the alliance of subgenus Platycercus (Violania) Wells & Wellington, 1992. Consequently, the two genera of Wells and Wellington, Violania and Hesperapsittacus, became synonymous with the subgeneric name of this species. This arrangement allies the western species to the "Platycercus eximius-adscitus-venustus" complex, which were separated to species by Les Christidis and Boles in 2008. The validity of the alliances in the subgeneric arrangement, especially of Platycercus (Violania), was tested in 2015, with a multilocus approach to phylogenetic analysis, and proposed a hypothesis that challenges the relationships within the genus.

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