New Zealand parrot

Systematics

No consensus existed regarding the taxonomy of Psittaciformes until recently. The placement of the Strigopoidea species has been variable in the past. This superfamily is one of three superfamilies in the order Psittaciformes; the other two families are Cacatuoidea (cockatoos) and Psittacoidea (true parrots). While some taxonomists include three genera (Nestor, Nelepsittacus and Strigops) in the family Strigopidae, others place Nestor and Nelepsittacus in Nestoridae and retain only Strigops in Strigopidae. Traditionally, the species of the superfamily Strigopoidea were placed in the superfamily Psittacoidea, but several studies confirmed the unique placement of this group at the base of the parrot tree.

Phylogeography

A hypothesis for the phylogeography of this group has been proposed and this provides a nice example of various speciation mechanisms at work. In this scenario, ancestors of this group became isolated from the remaining parrots when New Zealand broke away from Gondwana about 82 million years ago, resulting in a physical separation of the two groups. This mechanism is called allopatric speciation. Over time, ancestors of the two surviving genera, Nestor and Strigops, adapted to different ecological niches. This led to reproductive isolation, an example of ecological speciation. In the Pliocene, around five million years ago, the formation of the Southern Alps diversified the landscape and provided new opportunities for speciation within the genus Nestor. Around three million years ago, two lineages adapted to high altitude and low altitude, respectively. The high altitude lineage gave rise to the modern kea, while the low altitude lineage gave rise to the various kākā species. Island species diverge rapidly from mainland species once a few vagrants arrive at a suitable island. Both the Norfolk kākā as well as the Chatham kākā are the result of migration of a limited number of individuals to islands and subsequent adaptation to the habitat of those islands. The lack of DNA material for the Chatham kākā makes it difficult to establish precisely when those speciation events occurred. Finally, in recent times, the kākā populations at the North Island and South Island became isolated from each other due to the rise in sea levels when the continental glaciers melted at the end of the Pleistocene.

Until modern times New Zealand and the surrounding Islands were not inhabited by four-legged mammals, an environment that enabled some birds to adapt to make nests on the ground and others to become flightless.

The parakeet species belonging to the genus Cyanoramphus (kākārikis) belong to the true parrot family Psittacidae and are closely related to the endemic genus Eunymphicus from New Caledonia. They reached New Zealand between 450,000 and 625,000 years ago from mainland Australia by way of New Caledonia.

Species

Very little is known about the Chatham kākā. The genus Nelepsittacus consists of three described and one undescribed species recovered from early Miocene deposits in Otago.

Common names

All common names for species in this family are the same as the traditional Māori names. The word kākā derives from the ancient Proto-Polynesian word meaning parrot. Kākāpō is a logical extension of that name as pō means night, resulting in kākā of the night or night parrot, reflecting the species' nocturnal behaviour. The etymology of kea in Māori is less clear, and might be onomatopoeic of its call kee-aah.

In the anglicized versions of the names, the long versions of the vowels with diacritic marks, ā and ō, are replaced by a or o. In the Māori language, this changes the meaning of kākā from parrot to dress or clothing.

Ecology

The isolated location of New Zealand has made it difficult for mammals to reach the island. This is reflected in the absence of land mammals other than bats. The main predators were birds: eagles (Eyles' harrier, kāhu and Haast's eagle ), falcons (kārearea) and owls (whēkau and ruru). Many of the adaptations found in the avifauna reflect the unique context in which they evolved. This unique balance was disrupted with the arrival of the Polynesians, who introduced the Polynesian rat and the kurī (Polynesian dog) to the island. Later, Europeans introduced many more species, including large herbivores and mammalian predators.

The three extant species of this family occupy rather different ecological niches, a result of the phylogeographical dynamics of this family. The kākāpō is a flightless, nocturnal species, well camouflaged to avoid the large diurnal birds of prey on the island, while the local owls are too small to prey on the kākāpō at night. The kākāpō is the only flightless bird in the world to use a lek-breeding system. Usually, they breed only every 3–5 years when certain podocarp trees like rimu (Dacrydium cupressinum) mast abundantly.

The kea is well adapted to life at high altitudes, and they are regularly observed in the snow at ski resorts. As trees are absent in the alpine zone, they breed in hollows in the ground instead of in tree hollows like most parrot species.

Importance to the Māori

The parrots were important to the Māori in various ways. They hunted them for food, kept them as pets and used their feathers in weaving such items as their kahu huruhuru (feather cloak). Feathers were also used to decorate the head of the taiaha, a Māori weapon, but were removed prior to battle. The skins of the kākāpō with the feathers attached were used to make cloaks (kākahu) and dress capes (kahu kākāpō), especially for the wives and daughters of chiefs. Māori like to refer to the kākā in the tauparapara, the incantation to begin their mihi (tribute), because their voice (reo) is continuous.

Status

Of the five species, the Norfolk kākā and Chatham kākā became extinct in recent history. The last known Norfolk kākā died in captivity in London sometime after 1851, and only between seven and 20 skins survive. The Chatham kākā became extinct between 1550 and 1700 in pre-European times, after Polynesians arrived at the island, and is only known from subfossil bones. Of the surviving species, the kākāpō is critically endangered, with only 154 living individuals. The mainland New Zealand kaka is listed as endangered, and the kea is listed as vulnerable.

Threats

The fauna of Aotearoa (Māori for New Zealand) evolved for a long time in the absence of humans and other mammals. Only a few bat species and sea mammals were present prior to colonisation by humans, and the only predators were birds of prey that hunt by sight. These circumstances influenced the evolution of New Zealand's parrots, for example, the adaptations to flightlessness of the kākāpō and the ground breeding of the kea. Polynesians arrived at Aotearoa between 800 and 1300 CE, and introduced the kurī (dog) to the islands. This was disastrous for the native fauna, because mammalian predators can locate prey by scent, and the native fauna had not evolved a defence against them.

The kākāpō was hunted for its meat, skin and plumage. When the first European settlers arrived, the kākāpō was already declining but still widespread. The large scale clearance of forests and bush destroyed its habitat while introduced predators like rats, cats, and stoats found the flightless ground-nesting birds easy prey.

The New Zealand kākā is a species that needs large tracts of forest to thrive, and the continued fragmentation of forests due to agriculture and logging has a devastating effect on this species. Another threat comes from competition with introduced species for food, for example with possums for the endemic mistletoe and rātā and with wasps for shimmering honeydew, an excretion of scale insects. Females, young and eggs are particularly vulnerable in the tree hollows they nest in.

The kea nests in holes in the ground, again making it vulnerable to introduced predators. Another major threat, resulting from development of the alpine zone, is their opportunistic reliance on human food sources as their natural food sources dwindle.

Conservation

Recovery programs for the kākāpō and the kākā have been established, while the kea is also closely monitored. The 154 living kākāpō are all in a breeding and conservation program. Each one has been individually named.