New Zealand kaka

Taxonomy and naming

The New Zealand kaka was described by German naturalist Johann Friedrich Gmelin in 1788. There are two subspecies, the North Island kākā, Nestor meridionalis septentrionalis, and the South Island kākā, N. m. meridionalis. The name kākā is a Māori language word meaning "parrot", possibly related to kā, 'to screech'.

The genus Nestor contains four species: the New Zealand kākā (Nestor meridionalis), the kea (N. notabilis), the extinct Norfolk kaka (N. productus), and the extinct Chatham kaka (N. sp.). All four are thought to stem from a "proto-kākā", dwelling in the forests of New Zealand five million years ago. Their closest relative is the kakapo (Strigops habroptila). Together, they form the parrot family Strigopidae, an ancient group that split off from all other Psittacidae before their radiation.

Description

The New Zealand kākā is a medium-sized parrot, measuring 45 cm (18 in) in length and weighing from 390 to 560 g (14 to 20 oz), with an average of 452 g (0.996 lb). It is closely related to the kea, but has darker plumage and is more arboreal. The forehead and crown are greyish white and the nape is greyish brown. The neck and abdomen are more reddish, while the wings are more brownish. Both sub-species have a strongly patterned brown/green/grey plumage with orange and scarlet flashes under the wings; color variants which show red to yellow coloration especially on the breast are sometimes found.

This group of parrots is unusual, retaining more primitive features lost in most other parrots, because it split off from the rest around 100 million years ago.

The calls include a harsh ka-aa and a whistling u-wiia.

Distribution and habitat

The New Zealand kākā lives in lowland and mid-altitude native forest. Its strongholds are currently the offshore reserves of Kapiti Island, Codfish Island and Little Barrier Island. It is breeding rapidly in the mainland island sanctuary at Zealandia (Karori Wildlife Sanctuary), with over 600 birds banded since their reintroduction in 2002. From their reintroduction in 2002 the North Island Kākā continue to re-colonise Wellington and a recent report shows a significant increase in their numbers over the last 12 years.

Behaviour

Kākā are mainly arboreal and occupy mid-to-high canopy. Often seen flying across valleys or calling from the top of emergent trees. They are very gregarious and move in large flocks often containing kea where present.

Diet

The New Zealand kākā eats fruits, berries, seeds, flowers, buds, nectar, sap, plants and invertebrates. It uses its strong beak to shred the cones of the kauri tree to obtain the seeds. It has a brush tongue with which it feeds on nectar, and it uses its strong beak to dig out the grubs of the huhu beetle and to remove bark to feed on sap.

Nesting

New Zealand kākā make their nests in hollow trees, laying clutches of 2 to 4 eggs in late winter. Both parents assist in feeding the chicks. In a good fruiting year pairs can double clutch often utilizing the same nest hole for the second clutch. It is unusual for a pair to raise more than three chicks in a clutch.

Conservation status

The New Zealand kākā is considered vulnerable (CITES II). It has greatly declined across its traditional range as a result of habitat loss, predation by introduced predators like rats, possums and stoats, and competition from wasps and bees for the honeydew excreted by scale insects. A closely related species, Nestor productus, the Norfolk kaka, became extinct in 1851 for similar reasons.

Predation

Predatory mammals are responsible for the loss of an estimated 26 million native birds and their eggs each year in New Zealand.

As cavity nesters with a long incubation period that requires the mother to stay on the nest for at least 90 days, kākā are particularly vulnerable to predation. Stoats were the main cause of death of nesting adult females, nestlings and fledglings, but possums were also important predators of adult females, eggs and nestlings. There is strong evidence that predation of chicks and females has led to a serious age and sex imbalance, even amongst ostensibly healthy populations.

In parts of the country, the Department of Conservation and local conservation groups have attempted to control predators of kākā through the use of traps, ground baiting and the aerial deployment of sodium fluoroacetate (1080). Where pest control has been carried out, there has been significant recovery of kākā populations. For example, in Pureora Forest Park 20 kākā were radio-tracked in an area to be treated with aerial 1080 in 2001. In nearby Waimanoa Forest, which was not to be treated with 1080, nine kākā were radio-tracked. In the area where 1080 was used, all 20 birds survived that season. Of the nine birds tagged in the untreated area, five were killed by predators that same season.

Competition

Research has shown that honeydew is very important for breeding birds, especially those breeding in southern beech forests. The difficult nature of controlling the wasps makes the New Zealand kākā's future very uncertain.