| Rosella | |
|---|---|
 | |
| Adultcrimson rosella (P. elegans) | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Psittaciformes |
| Family: | Psittaculidae |
| Tribe: | Platycercini |
| Genus: | Platycercus Vigors, 1825 |
| Type species | |
| Psittacus pennantii[1] Latham, 1790 | |
| Species | |
Rosellas/roʊˈzɛləz/[2] are in a genus that consists of sixspecies and nineteen subspecies. These colourfulparrots from Australia are in the genusPlatycercus.Platycercus means "broad-tailed" or "flat-tailed",[3] reflecting a feature common to the rosellas and other members of thebroad-tailed parrot tribe. Their diet is mainly seeds and fruit.
The genus was described by naturalistNicholas Aylward Vigors in 1825; the namePlatycercus derived from theGreekplatykerkos meaning "broad-" or "flat-tailed", fromplatys "broad, wide, level, flat" andkerkos "tail of a beast".[3][4][5] The relationships with other parrots have been unclear, with the Australian ringneck (genusBarnardius) cited as a closest relative by some, and the genusPsephotus by others; the plumage of the western rosella seen as a link to the latter genus.[6]
Early European settlers encountered theeastern rosella atRose Hill, New South Wales, nowParramatta, and so they called it the Rosehillparakeet which became "Rosehiller", and eventually "rosella".[7] Vigors defined the genusPlatycercus in 1825, based on
the distinctive architecture of the feathers in the tail and wing, and designated the crimson rosellaPlatycercus elegans (asPlatycercus pennantii) as thetype species.[4] The description as a flat or broad tail followsHeinrich Kuhl, who separated his psittacine specimens to a group with tails that were "narrow and cuneated", that is, a tapering wedged outline.[5]
There are, broadly speaking, three groups of rosella species. They are the blue-cheeked species which includeselegans andcaledonicus, the white-cheeked species,eximius,adscitus andvenustus and the yellow-cheeked species,icterotis. The observed difference in plumage has been reinforced by molecular studies in 1987 and 2015 that place theicterotis as a basal offshoot.[8]
There are six species and many subspecies:[9] Ovenden and colleagues analysed mitochondrial DNA, confirming the blue-cheeked and white-cheeked lineages. They foundP. caledonicus to be basal to the other blue-cheeked forms, withP. elegans nigrescens being divergent from other subspecies ofP. elegans. Also,P. venustus was basal toP. eximius andP. adscitus.[8] However, a mitochondrial study published in 2017 found thatP. eximius was the earlier offshoot of the lineage that split intoP. adscitus andP. venustus, and that nonsister taxa were hence able to hybridise.[10] In 2015, Ashlee Shipham and colleagues published a molecular study based on nuclear DNA finding thatP. venustus andP. adscitus were sister species, and thatP. elegans nigrescens diverged earlier thanP. caledonicus.[11]
| Common name | Scientific name and subspecies | Range | Size and ecology | IUCN status and estimated population |
|---|---|---|---|---|
| Green rosella
| Platycercus caledonicus (Gmelin, 1788) Two subspecies
| Tasmania | Size: 37 cm (15 in) long, the largest rosella. It has a yellow head and underparts with blue cheeks and a red frontal band above the bill. The feathers on the back and inner wings are black with narrow green margins at their tips, and the outer wing feathers are blue and green. Rump olive and the tail green. Irises are dark brown and the bill is light grey.[12] Habitat: Diet: | LC |
| Crimson rosella
| Platycercus elegans (Gmelin, 1788) Eight subspecies
| East and Southeast Australia | Size: 36 cm long, seven subspecies, three of which are actually crimson. The red is replaced by yellow in the case of var. flaveolus and a mixture of red, orange and yellow in the Adelaide rosella. Habitat: Diet: | LC |
| Northern rosella
| Platycercus venustus (Kuhl, 1820) Two subspecies
| Gulf of Carpentaria, through Arnhem Land to the Kimberleys in open savannah country, Australia. | Size: 28 cm long, forehead, crown and nape are black in colour with white-on-blue cheek-patches. The back and wing feathers are blackish with yellow borders, while the feathers of the belly, chest and rump are pale yellow with black borders giving rise to a scalloped appearance, tail is bluish green. The bill is pale grey. Habitat: Diet: | LC |
| Pale-headed rosella
| Platycercus adscitus (Latham, 1790) Two subspecies
| Eastern Australia | Size: 30 cm long, mostly covered in blue except for the upper breast and head which are cream-yellow, the tail is blue-black and green, and an area around the vent is red. Habitat: Diet: | LC |
| Eastern rosella
| Platycercus eximius (Shaw, 1792) Three subspecies
| Australia and Tasmania. Introduced to New Zealand where feral populations are found in most of the North Island and the hills around Dunedin in the South Island[13] | Size: 30 cm (12 in) long. Red head and white cheeks. The upper breast is red and the lower breast is yellow fading to pale green over the abdomen. The feathers of the back and shoulders are black, and have yellowish or greenish margins giving rise to a scalloped appearance that varies slightly between three subspecies and the sexes. The wings and lateral tail feathers are bluish while the tail is dark green.[14] Habitat: Diet: | LC |
| Western rosella
| Platycercus icterotis (Temminck & Kuhl, 1820) Two subspecies
| Southwest Australia | Size: 26 cm (10 in) long, the smallest rosella. The male is mainly red with yellow cheek patches, green rump, and a dark green tail. The female is duller, with a mainly green head, reddish forehead, yellow cheeks, and variegated green-red underparts. Colours of scalloped back feathers differ between two subspecies. The bill is whitish and the irises are dark brown.[14] Habitat: Diet: | LC |
Ranging in size from 26–37 cm (10–14+1⁄2 in), rosellas are medium-sized parrots with long tails.[12] The feathers on their backs show an obvious scalloping appearance with colouring that differs between the species.[12] All species have distinctive cheek patches.[12]Sexual dimorphism is absent or slight – males and females generally have similar plumage, apart from thewestern rosella.[6] The juveniles of the blue-cheeked species, and western rosella, all have a distinctive green-based plumage, while immature plumage of the white-cheeked species is merely a duller version of the adults.[6]
Rosellas are native to Australia and nearby islands, where they inhabit forests, woodlands, farmlands, and suburban parks and gardens. They are confined to the coastal mountains and plains and are absent from theoutback. Introduced populations have also established themselves inNew Zealand (notably in theNorth Island and in northDunedin) and onNorfolk Island.
Rosellas feed predominantly on seeds and fruit, with food held in the foot. They enjoy bathing in puddles of water in the wild and in captivity.[15] Rosellas scratch their heads with the foot behind the wing.[15]
Mutual preening is not exhibited by the genus, and the courtship display is simple; the male waves his tail sideways, and engages in some head bobbing, and the female reciprocates.[6]
Like most parrots, they are cavity nesters, generally nesting high in older large trees in forested areas. They generally have aclutch size of several eggs which are incubated for around 21 days by the female alone. The male feeds the female through this time and for some time after incubation concludes. Quickly covered in a white down, chicks take around five weeks tofledge.[6]
The more colourful rosella species are popular aspet parrots and also as aviary birds. They can live for longer than 20 years, and they are relatively easy to breed.[16] All have a reputation for being aggressive in captivity, and are hence recommended be kept separate from other caged birds. Their diet in aviculture includes seeds, fruit such as apple, pear, and grapes, and vegetable matter such as lettuce, grass, and silver beet.[15]
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