Story: Introduced land birds
Page 3 – Cockatoos and rosellas
Four introduced members of the parrot family have established themselves in New Zealand.
The penetrating screech of a sulphur-crested cockatoo (Cacatua galerita) means it is often heard before it is seen. It is mainly white, but has pale yellow on its crest, under-wing and under-tail feathers.
Sulphur-crested cockatoos are native to parts of Australia and New Guinea. Popular as cage-birds, they were reported in the wild in the Waitākere Ranges in the early 1900s. A hundred years later one population is still centred there, with others in western Waikato, the Turakina–Rangitīkei region, Wellington region and Banks Peninsula.
Occasionally, individual birds are seen further afield – possibly cage escapees, deliberate releases or stragglers from across the Tasman. The total wild population may be fewer than 1,000 birds.
Sulphur-crested cockatoos have a heavy parrot bill, which they use to break open large nuts and seeds. They also eat fruit and berries, bulbous roots, grains, flowers, leaf buds and insect larvae. They roost and nest in bush, but sometimes feed on adjoining farmland so they are often considered a pest.
They usually build their nests high up in tree hollows lined with wood chips, where they lay two or three white eggs.
After the breeding season, cockatoos gather in large flocks. While the main group feeds, a few sentinels perched high up screech to warn of intruders.
The galah (Eolophus roseicapillus), native to Australia, is a pink cockatoo with grey wings. Cage escapees have established a small population centred on Pōnui Island and the nearby Hūnua district – probably fewer than 100 birds.
A parrot native to south-east Australia, the eastern rosella (Platycercus eximius) is about 25 centimetres long and 110 grams in weight – larger than most native New Zealand parakeets.
It has distinctive white cheeks against a red head, face and chest. The underbody is yellow, while its wings and long tail are indigo to green. Eastern rosellas call a ringing ‘kwink kwink’ as they fly, and they also chatter and screech. They have a two-note whistle similar to that of a bellbird.
A shipment of eastern rosellas, and a few crimson rosellas, was released off the Otago heads around 1910, after being denied entry by customs officials. By the early 2000s this Dunedin population was the main South Island group of eastern rosellas.
A separate population was established near Auckland prior to 1920, and another in Wellington around 1960. Eastern rosellas are now widespread in the southern North Island and north of Taupō. They are found mainly in open forest, urban parks, farmland, gardens and orchards.
Crimson rosellas (Platycercus elegans) are popular cage birds, but are probably extinct in the wild in New Zealand. Adults are crimson with blue cheeks, wings and tail, while juveniles are green with red crown, bib and undertail. At about 130 grams and 35 centimetres, they are slightly heavier and longer than the eastern rosella.
The few crimson rosellas released with eastern rosellas near Otago heads became established, but the two species interbred. By the early 2000s only eastern rosellas were seen there.
Cage escapees and their descendants were seen from 1963 in a few leafy parks and suburbs of Wellington, but had apparently died out by the mid-1990s.