Strigopidae – New Zealand Parrots

There was no complete consensus regarding the taxonomy of Psittaciformes until recently. The placement of the Strigopoidea species has been variable in the past. The family belongs to its own superfamily Strigopoidea. This superfamily is one of four superfamilies in the order Psittaciformes; the other three families are Cacatuoidea (Cockatoos), Psittacidae (African & New World Parrots) and Psittaculiudae (Old World Parrots).

The New Zealand parrot family, Strigopidae, now consists of just two genera of parrots – Nestor & Strigops. The genus Nestor consists of just two species, the Kea, and Kākā, while the genus Strigops only has one species, the Kākāpō. All extant species are endemic to New Zealand. There were (extinct) species of the genus Nelepsittacus endemics of the main islands, while the two extinct species of the genus Nestor were found at the nearby oceanic islands such as Chatham Island of New Zealand, and Norfolk Island and adjacent Phillip Island.

The family diverged from the other parrots around 82 million years ago when New Zealand broke off from Gondwana, while the ancestors of the genera Nestor and Strigops diverged from each other between 60 and 80 million years ago.

The Kea and the New Zealand Kaka are large, stout parrots with strong and heavily hooked bill. The Kea has olive-green plumage with conspicuous orange underwings and rump. The tail is broad and square. The female has shorter bill and the juvenile has yellow cere and eye-ring instead of grey. The New Zealand Kaka has brown and red plumage and whitish crown. However, the subspecies N.m. septentrionalis is duller with pale grey crown. The bill is massive with elongated upper mandible. The female has browner face and shorter bill. The juvenile has paler eye-ring.

The Kakapo is the largest parrot. The broad, rounded wings are rudimentary and the bird is flightless. Its plumage is green with yellow and brownish mottling, and yellower pattern on the underparts. It has distinctive flat, owl-like face with conspicuous facial disk and rictal-bristles around the bill base. The female is smaller than the male, and the juvenile resembles adults with pale brownish face and underparts. They are nocturnal.

Both Kea and Kaka feed on seeds, fruits, nectar, insects and their larvae, but the Kea also regularly scavenges at rubbish dumps. The Kakapo is vegetarian and feeds exclusively on a variety of plant matter. They feed on the ground and in trees, often in groups, although the Kakapo is more solitary. This terrestrial bird climbs branches and trees and may glide over short distance from the tree to the ground. Unlike the Kakapo, the other species are powerful fliers. During the flight, the red underwings are conspicuous. They frequent dense forest, even high in mountains for the Kea which can be seen from the lower valleys to the steep mountains. This species occurs in the mountains of South Island.

The New Zealand Kaka frequents the forests with mature trees, and occurs from 450 to 1000 metres of elevation. The two subspecies share the New Zealand range, including large offshore islands.

The Kakapo is now living on forested islands but formerly, it was present from Podocarp Forest in lowland, to Notophagus in upland beech forest and subalpine scrublands in New Zealand. Now, this species survives where it has been introduced in predator-free offshore islands.

The Strigopidae can be noisy, like all Psittaciformes. The Kea gives far-carrying “keee-aah” in flight, while soaring high in the air. On the ground, they communicate by soft sounds and whistles. The New Zealand Kaka also calls in flight, giving harsh, grating “kraa-aa” and other sounds including a variety of yodelling notes. Hence the onomatopoeic names.

The Kakapo has unique voice among parrots. The male produces low-frequency, far-carrying bittern-like booming while displaying at lek. It lowers its head and inflates the thoracic air-sacs in order to produce descending grunts leading to loud booming calls. Some other strange sounds can be heard too.

Their breeding behaviour differs from each other. The Kea is polygamous. The males fight for hierarchy and dominance. These hierarchies are not linear. An adult male may dominate a subadult, but a juvenile male may be dominant to an adult male. They nest under rocks or logs, or in cavities among boulders or tree roots. The female lays 2-4 eggs in the nest made with sticks, grasses and moss, between July and January. Both parents raise the chicks. The Kaka performs some displays which enhance the bright red underwings. This species nests in cavities in mature trees, lined with powdery wood dust. The 3-4 eggs are laid between September and March. The male feeds the female during the incubation, and then, both parents raise the chicks.

The Kakapo has unique breeding behaviour and uses a lek. It creates shallow depressions in the earth, and may have up to 10 bowls from which it attracts females with deep, booming calls. The female enters a bowl and chooses a male. However, no pair-bond is established. The male does not take part in nesting duties. The female forms a scrape in a hollow protected by log or under tussock. She lays 2-3 eggs and raises the chicks alone between November and February.

The Strigopidae move according to the food resources but they are sedentary in their range. The Kakapo may walk over several kilometres by night. Kea and Kaka sometimes perform altitudinal movements after breeding. The juveniles may wander after the breeding season.

All three species have small populations, due to introduced mammalian predators such as cats, rats and stoats. Forest clearance and degradation of the habitat affected these species which live in forest and dense vegetation, like hunting and sometimes pet trade in the past. In addition, they are living in restricted range. The Kea’s population is estimated at about 3,300 mature birds and decreasing. The species is listed as Vulnerable. The Kaka’s population is around 1,500 to 7,000 individuals. It is classified as Endangered. The Kakapo’s population (2025) is very small with 243 individuals including c.116 adults capable of breeding. The species is Critically Endangered. Conservation measures have allowed some slow increase of these small populations. Birds have been translocated and introduced to forested, offshore, predator-free islands where they can breed and raise their chicks safely.

NB The parakeet species now in New Zealand belonging to the genus Cyanoramphus (kākāriki) belong to the true parrot family Psittacidae and are closely related to the endemic genus Eunymphicus from New Caledonia. They may have reached New Zealand between 450,000 and 625,000 years ago from mainland Australia by way of New Caledonia, but this is disputed.