Green Rosella

A green rosella specimen was collected in Adventure Bay, Tasmania, by ship's surgeon William Anderson on the third voyage of James Cook between 26 and 30 January 1777. Anderson collected many bird specimens while tasked as the expedition's naturalist, although he died of tuberculosis in 1778 before the return home. Many collection localities were incorrect, and notes were lost or pieced together many years later. The specimen, along with many others, ended up in the collection of British naturalist Sir Joseph Banks. English naturalist John Latham saw it there and wrote about the green rosella in his 1780s work A General Synopsis of Birds. He called it the Caledonian parrot as he assumed (incorrectly) it came from New Caledonia. He even suspected it might be the female of the horned parakeet, which he also saw in Banks' collection. Latham did not give them binomial names, however. It was left to German naturalist Johann Friedrich Gmelin to describe the species, which he did as Psittacus caledonicus in the 13th edition of Systema Naturae in 1788. In 1820, German naturalist Heinrich Kuhl described a specimen that Robert Brown had collected from northwestern King Island on 23 April 1802 during Matthew Flinders' circumnavigation of Australia, naming it Psittacus brownii in honour of its collector. He based it on the description of la Perruche à large queue, "the long-tailed parrot" by French naturalist François Levaillant in his 1805 work Histoire Naturelle des Perroquets. Kuhl's name also took priority over Dutch zoologist Coenraad Jacob Temminck's published name of Psittacus flavigaster, Irish zoologist Nicholas Aylward Vigors established the genus Platycercus in 1825, based on the distinctive architecture of the feathers in the tail and wing, including P. flavigaster and P. brownii within it. English naturalist James Francis Stephens named it Platycercus xanthogaster in 1826, though there was no need for a new binomial name. Mathews did feel the King Island form was distinctive, being larger and having more red in the plumage than Tasmanian populations and so described it as P. c. henriettae in 1915. "Green rosella" has been designated the official name by the International Ornithological Committee (IOC). Alternative common names include Tasmanian rosella, yellow-breasted parakeet and mountain parrot. English zoologist John Gould called it the yellow-bellied parakeet, and early Tasmanian settlers knew it as the hill parrot. In 2015, Ashlee Shipham and colleagues published a molecular study based on nuclear DNA finding that the North Queensland crimson rosella diverged earlier than the green rosella. They also estimated that the green rosella had diverged from the main crimson rosella lineage around 0.5 million years ago.

Found across Tasmania and Bass Strait islands, the green rosella is one of the commonest birds encountered. It also occurs on offshore islands such as Maria, Bruny, De Witt and Maatsuyker Islands. Its movements have not been much studied. Although possibly locally nomadic in places, the green rosella is sedentary; even birds at higher altitudes do not migrate. It has become rare on King Island, due to land clearing and possibly competition with the introduced common starling (Sturnus vulgaris) for nesting sites. During breeding season there it is restricted to the Pegarah forest, though may venture elsewhere at other times. It lives in most habitats with some form of tree cover up to 1500 m (5000 ft) above sea level. These include temperate Southern beech rainforest (where it generally keeps to the canopy), wet and dry sclerophyll forest, woodland, Melaleuca shrubland, coastal heath, dwarf alpine conifer forest, sedgeland, buttongrass moors, tussock grassland, as well as fields, orchards and urban parks and gardens.

Green rosellas are generally encountered in pairs or small groups, though young birds may gather in groups of 20 or more outside the breeding season. They sometimes share the company of eastern rosellas. They fly in a straight line, making rapid shallow wingbeats and gliding briefly in between. The green rosella has a repeated two-syllable contact call, which has been written as kussik kussik or cossack cossack and is heard in flight. When perched, it utters a rising kwik-kweek kwik-kweek contact call. Birds also make a chattering call during courtship. They can screech shrilly when alarmed.

The green rosella generally breeds at two years of age, though younger birds may pair up and look for nests. The breeding season is September to January, with one brood. The nesting site is usually a hollow over 1 m (3 ft) deep in a tree trunk anywhere up to 30 m (100 ft) above the ground. The tree chosen is generally a eucalypt such as Tasmanian bluegum, manna gum or mountain ash (E. regnans), or myrtle beech. Chimneys, holes in walls and even the vertical pipes of tennis court fences have been used. Green rosellas nested in a wall cavity at Port Arthur convict prison site in 1958 and 2009. Laying takes place in September and October. A clutch of four or five white and slightly shiny eggs, measuring 30 x 24 mm, is laid. The incubation period has been recorded as anywhere from 19 to 23 days, with the female performing this duty alone. Newly hatched chicks are covered with long white down, and are largely helpless (nidicolous). They leave the nest four to five weeks after hatching and join up with other young birds in flocks, though rely on their parents for food for another fortnight after fledging.

The green rosella is predominantly herbivorous, with the seeds of grasses and trees—especially eucalypts—forming the bulk of its diet; other items eaten include the seed of the soft tree fern (Dicksonia antarctica), cranberry heath (Astroloma humifusum), myrtle beech (Lophozonia cunninghamii), Australian blackwood (Acacia melanoxylon), silver wattle (Acacia dealbata) and buttercups (Ranunculus), berries, nuts and fruit, as well as flowers and new buds of southern sassafras (Atherosperma moschatum), mānuka (Leptospermum scoparium), shining tea-tree (Leptospermum nitidum), swamp honey-myrtle (Melaleuca squamea), Tasmanian bluegum (Eucalyptus globulus), Smithton peppermint (Eucalyptus nitida), messmate stringybark (Eucalyptus obliqua), snow gum (Eucalyptus pauciflora), manna gum (Eucalyptus viminalis), small-fruit hakea (Hakea microcarpa) and native plum (Cenarrhenes nitida). The green rosella has at times partaken of the berries of the common hawthorn (Crataegus monogyna), as well as Coprosma and Cyathodes, and even leaf buds of the common osier (Salix viminalis). It may eat insect larvae and insects such as psyllids of the genus Schedotrioza, which they extract from leaf galls on the black peppermint (Eucalyptus amygdalina). Green rosellas generally forage in the canopy or understory of forested areas, or in hedges, shrubs and trees in more open areas. They come to the ground to eat fallen fruit or spilt grain in orchards or farmland. They keep quiet while on the ground, and are quite noisy when in trees. Green rosellas forage in pairs or small groups of under 20 individuals, though larger groups of 50 to 70 have been observed at stands of blackberries or thistles in fields. When feeding, they generally hold food items in their left feet and extract edible parts or break and discard nut shells with their beaks.

Gould noted that early Tasmanian settlers regarded the abundant green rosella highly as food; he agreed that it was very tasty after trying it himself. and its population thought to number fewer than 500 birds. Around 70% of King Island's native vegetation has been cleared, and the remainder is highly fragmented and at risk of too-frequent bushfires.

Green rosellas were regularly captured and kept as pets until the early 20th century. The species is reported to be hardier and easier to keep in captivity than other rosellas. However, it is not a popular bird in the aviary trade, possibly on account of its subdued colours.

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