The Psittacidae comprise the parrots and lories; a group of over three hundred (typically brightly coloured) species with distinctive hooked bills, distributed on all continents except Antarctica. The monotypic Kakapo is the only member its own subfamily, Strigopinae. This unusually large parrot is one of just seven parrot species endemic to New Zealand. It is also the only flightless parrot in the world, and one of the few exclusively nocturnal ones. Together with the Kea (Nestor notabilis) and Kaka (Nestor meridionalis), two other large parrots endemic to New Zealand, they form a long thin branch of the bird evolutionary tree.
The tree below shows the evolutionary relationships between this species and all other birds. The colours of the tree indicate EDGE scores with the red shades indicating the higher priority species; the bright red leaves correspond to the top 100 EDGE bird species. Further information on every species can be found by zooming in to its leaf on the tree.
Weight: 2,000g (up to 4,000g in the breeding season)
This large, charismatic parrot blends perfectly into the background of the native New Zealand vegetation. The plumage on its back is moss green with black barring, whilst its underparts are more yellowy green. All the feathers are mottled brown and yellow ensuring it is camouflaged against the forest surroundings. This cryptic colouration may have evolved because of predation from the giant, now extinct Haast’s eagle. The Kakapo has a distinctive owl-like facial disc made up of light yellow to brown hair-like feathers. Its eyes are dark brown and its short, broad bill is a light blue-grey colour. The wings are short, as is the tail, whilst the legs are large and muscular.
Females are smaller than males with a narrower head, proportionately longer bill and tail, and pinker legs and feet. Their weight is typically about 65% that of the males. Males can weigh up to as much as 3.6kg meaning they are the world’s heaviest parrot. The body mass of both sexes fluctuates throughout the year, due to storage and mobilisation of fat reserves. An increase of between 60-100% bodyweight is gained in preparation for the breeding season. This magnitude of weight gain is greater than that of any other terrestrial bird.
Kakapo are well known for the male’s ‘booming’ call, which he repeats during the night in the breeding season, to attract a female. At such a low wavelength, these foghorn-like notes can be heard as far as 5km away. Although generally a quiet bird, both sexes sometimes make repeated, high-pitched noises (sounding like ‘skraark), which become more frequent in the breeding season. During territorial confrontations, the birds will squeal, screech and grunt. The bird also gives off a very distinctive sweet odour.
The Maori name, ‘Kakapo’ means ‘night parrot’ reflecting the bird’s nocturnal behaviour. The Kakapo is flightless and runs through the forest on its strong, muscular legs. The species is surprisingly adept at climbing, hauling its great weight up trees using a powerful beak and by flapping its short wings can jump to the ground from as high as 15 metres without injury. These herbivorous birds forage in the tree tops for fruit and on the ground for the leaves, roots, bark and seeds from a number of native plant species. This varied diet enables them to inhabit a variety of habitat types. With a mean lifespan of 90 years (in the absence of predators), they are the world’s longest living bird as well as exhibiting the lowest energy expenditure of any bird.
The Kakapo can be found in a range of habitats of varying altitudes and climates, including forest, scrub, herb fields and tussock grassland. The species has also adapted to unfamiliar habitats, including pastureland.
Thanks to intensive management and conservation efforts by the Kakapo Recovery Programme, numbers have increased from 51 known individuals in 1995 to a slowly increasing population of 125.
The main factors that have caused the decline of this charismatic species are hunting and the introduction of alien predators. The Kakapo was once widespread and common across New Zealand with its only natural predator being the giant Haast’s Eagle, which hunted by sight. The Kakapo’s camouflage and method of avoiding predation – remaining motionless – worked well to evade capture by this visual predator. However, a few thousand years ago the Maoris arrived in New Zealand and the bird made easy prey for hunters. The arrival of European settlers 150 years ago further exacerbated the population decline, due to the introduction of stoats, cats, dogs and rats. These predators seek prey using smell, meaning the Kakapo, with its unique odour, was defenceless against these introduced animals. Rats preyed upon the Kakapo eggs, having a huge impact on the species’ reproductive success. Much of the Kakapo’s natural habitat was burnt and cleared to make way for agriculture and areas that remained were degraded by introduced herbivores. Combined, these factors have led to a catastrophic decline in Kakapo numbers. The once common species now only persists on three small, intensively-managed islands that have undergone predator-eradication programmes.
The Department of Conservation (DOC) New Zealand undertook eradication programmes on Codfish and Anchor Island to exterminate rats and stoats, turning the islands into sanctuaries for the recovery of the Kakapo and other native birds. A dedicated team from the Kakapo Recovery Programme now monitors and protects all Kakapo. In a ten year plan from 2006-2016 they hope to grow Kakapo numbers so that populations can be established on other offshore, managed islands. Indeed in 2012, eight individuals were taken to Little Barrier Island in a trial attempt to create a third breeding population. Management includes preventing closely related individuals mating and increasing the number of progeny of birds with rare genes, thus ensuring the greatest amount of genetic diversity is maintained within the population.
The Kakapo Recovery Programme will continue to monitor and breed species as described above. They also plan to secure and restore other island refuges to provide habitat for the hoped increase in Kakapo numbers. Eventually, in the very distant future, they plan to reintroduce the species to the mainland.
BirdLife International (2013) Species factsheet: Strigops habroptila. Downloaded from www.birdlife.org on 28/01/2013
BirdLife International (2012). Strigops habroptila. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2. www.iucnredlist.org. Downloaded on 28/01/2013
de Kloet, R.S. and de Kloet, S.R. (2005) The evolution of the spindlin gene in birds: Sequence analysis of an intron of the spindlin W and Z gene reveals four major divisions of the Psittaciformes. Molecular Phylogenetics and Evolution 36:3 pp706-721.
Donald, P.F., Collar N. J., Marsden S. J. and Pain D. J. (2010) Facing Extinction. The World’s rarest birds and the race to save them. T & A.D. Poyser, London.
Hagelin, J. C. (2004), Observations on the olfactory ability of the Kakapo Strigops habroptilus, the critically endangered parrot of New Zealand. Ibis, 146: 161–164.
Kakapo Recovery Programme (2013) Downloaded from www.kakaporecovery.org.nz on 28/01/2013
Steiger, S., Fidler, A. and Kempenaers, B. (2009) Evidence for increased olfactory receptor gene repertoire size in two nocturnal bird species with well-developed olfactory ability. BMC Evolutionary Biology 9(1):117
Text compiled by Michelle Harrison. Factchecked by Ron Moorhouse.