Story: Large forest birds
Page 5 – Kākāpō
The kākāpō (Strigops habroptilus) – literally ‘parrot of the night’ in Māori – is famous worldwide for its unusual behaviour, size and rarity. This large, flightless parrot is so different from other parrots that it has its own endemic subfamily, Strigopinae. It has a soft moss-green cloak flecked with brown and yellow, and round patches of pale feathers around each eye which give it an owlish appearance.
At a maximum weight of 4 kilograms (although averaging 2 kilograms), the male kākāpō is the heaviest parrot in the world. The average weight of females is 1.5 kilograms. Like other parrots, it has two forward-pointing and two backward-pointing toes, which it uses like a hand to cling to branches or grasp food. The herbivorous kākāpō eats large quantities of forest fruit, seeds, leaves and roots.
Long-lived slow breeders
Kākāpō live at least 60 years, maybe 100, and do not breed every year. To breed they require abundant food supplies – especially fruit – to support hungry chicks. Such prolific ‘mast’ fruiting only occurs every few years. Kākāpō are vulnerable to predators, and in 1995 there were just 51 known survivors. Determined conservation efforts have stopped the decline. In 2005 there were 86 kākāpō, and in 2011 there were 129, including 11 chicks born that year.
The male kākāpō’s booming call can be heard as far as 5 kilometres away. One was recorded making 17,000 booms in one night. Some birds keep this up for three months – a feat that they can only achieve with an adequate diet.
Booming and breeding
To breed, males gather in a ‘booming arena’ in summer, between December and March. They inflate their air sacs and make a low booming sound which carries far into the night to attract mates. As females arrive, males compete for their attentions.
Attracting females to a central courtship arena is known as a lek system of breeding. The kākāpō is the only parrot that breeds in this way.
After mating, the female makes a nest, hatches two to four eggs, and feeds the young – while the male goes his solitary way until the next breeding season. Juveniles are vulnerable to predators because the female has to leave the nest at night to search for food, sometimes jogging several kilometres two or three times a night. The kākāpō breeding cycle spans five months, leaving the female’s reserves severely depleted.
Kākāpō or volcano?
The geologist James Park travelled to Dusky Sound in 1890. He wrote that his companion, the explorer William Docherty, supposedly knew kākāpō well, yet failed to recognise their booming as the call of a bird. ‘So sudden and startling was the sound that he maintained to the last that it was a subterranean noise in some way connected with volcanic action.’ 1
In 1899, the explorer Charlie Douglas forecast that the kākāpō was ‘doomed to extinction long before the Kiwi and the Roa [great spotted kiwi] are a thing of the past’.
Partial to boiled kākāpō himself, Douglas noted that ‘they could be caught in the moonlight, when on the low scrub, by simply shaking the tree or bush till they tumbled on the ground, something like shaking down apples. I have seen as many as a half a dozen Kakapos knocked off one tutu bush this way.’ 2
He noted their decline through Westland as introduced predators spread. Kākāpō were already extinct in the North Island by the 1840s, their fate sealed by Māori hunting.
In the 1890s, concerned about plummeting numbers of kākāpō, conservationist Richard Henry transferred hundreds to an inshore Fiordland island. But they lost the battle when stoats invaded, swimming the short distance from the mainland.
Brink of extinction
During the 20th century, kākāpō numbers dropped steeply, almost to extinction. Between 1974 and 1977, 18 birds – all males – were found in Fiordland. Then in 1977, miraculously, a population of up to 200 male and female birds was found in a remote part of Stewart Island. This group boosted hopes for the species’ survival, but it was being decimated by feral cats.
Both Māori and Europeans found that kākāpō made affectionate pets. Governor George Grey wrote to a friend about a pet kākāpō which acted more like a dog than a bird in its interactions with humans. A lighthouse keeper at Puysegur Point in Fiordland had a kākāpō called Major, which used his dog, Hector, ‘as a cushion to sleep upon … As soon as [Major] had had sufficient sleep, he began to pull the dog’s ears, nose, tail, toes, and hair, running all over his body, apparently to Hector’s thorough enjoyment.’ 3
Conservation efforts from the 1950s to the 1980s focused on finding kākāpō and moving them to safety. At first a few birds placed in captivity died, but others that were set free on island sanctuaries such as Codfish Island, west of Stewart Island, have formed the nucleus of a successful breeding programme. Years of research to develop effective management strategies, along with eradicating pests from island sanctuaries, have increased the success rate of breeding and raising chicks.
To encourage kākāpō to breed, conservation managers supplemented their natural diet with nuts and fruit. However not until a bumper fruiting year of rimu trees in 2002 did the population increase significantly – from 62 to 86.