The Takahē or South Island Takahē (Porphyrio hochstetteri) is a flightless bird indigenous to New Zealand and belonging to the rail family. It was thought to be extinct after the last four known specimens were taken in 1898. However, after a carefully planned search effort the bird was rediscovered by Geoffrey Orbell near Lake Te Anau in the Murchison Mountains, South Island, on 20 November 1948. The specific scientific name commemorates the Austrian geologist Ferdinand von Hochstetter.
Taxonomy and systematics
A related species, the North Island Takahē (P. mantelli) or mōho is extinct and only known from skeletal remains. Both forms were long assumed to be subspecies of mantelli, and were usually placed in the genus Notornis. However, it has been determined that the differences between Porphyrio and Notornis were insufficient for separating the latter, whereas the differences between the North and South Island forms justified the splitting into two species, as each evolved independently towards flightlessness.
The Takahē is the largest living member of the Rallidae family. Its overall length averages 63 cm (24.8 in) and its average weight is about 2.7 kg (6 lbs) in males and 2.3 kg (5 lb) in females, ranging from 1.8-4.2 kg (4-9.2 lbs). The standing height is around 50 cm (20 in). It is a stocky bird, with reduced wings, strong legs and a massive bill.
The adult Takahē is mainly purple-blue in colour, with a greenish back and inner wings. It has a red frontal shield and red-based pink bill. The legs are pink. Sexes are similar, the females being slightly smaller, but young birds have mainly pale brown plumage. Immatures have a pinkish bill with bluish cast.This is a noisy species with a loud clowp call. Contact call is easely confused with that of the Weka (Gallirallus australis), but is generally more resonant and deeper.
Distribution and habitat
The species is still present in the location where it was rediscovered in the Murchison Mountains. Small numbers have also been successfully translocated to four predator-free offshore islands, Tiritiri Matangi, Kapiti, Maud and Mana, where they can be viewed by the public. Additionally, captive Takahē can be viewed at Te Anau and Mt Bruce wildlife centres. In June 2006 a pair of Takahē were relocated to the Maungatautari Restoration Project. In January 2011 two Takahe were released in Zealandia, Wellington.
Behaviour and ecology
The Takahē is a sedentary and flightless bird currently found in alpine grasslands habitats. Although it is indigenous to swamps, humans turned its swampland habitats into farmland, and the Takahē was forced to move upland into the grasslands. It holds territories in the grassland until the arrival of snow, when it descends to the forest or scrub. It eats grass, shoots and insects, but predominantly leaves of Chionochloa tussocks and other alpine grass species. The Takahē can often be seen to pluck a snow grass (Danthonia flavescens) stalk, taking it into one claw and eating only the soft lower parts which is a favourite food. The rest is discarded.
The Takahē is monogamous (with pairs remaining from 12 years to, probably, their entire lives) builds a bulky nest under bushes and scrub and lays two buff eggs. It is territorial. The chick survival rate is 73-97%. Recently, human intervention has been required to maintain the breeding success of the Takahē. For the success of fledgling Takahē is relatively low in the wild compared to other, less threatened species, so methods such as the removal of infertile eggs from nests and the captive rearing of chicks have been introduced to manage the Takahē population. The Fiordland Takahē population has a successful degree of reproductive output due to these management methods: the number of chicks per pairing with infertile egg removal and captive rearing is 0.66, compared to 0.43 for regions without any breeding management.
Status and conservation
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Formerly widespread, the near-extinction of the Takahē is due to a number of factors: over-hunting, loss of habitat and introduced predators have all played a part. The introduction of red deer (Cervus elaphus) represent a severe competition for food, while the stoats (Mustela erminea) take a role as predators. The spread of the forests in post-glacial Pleistocene-Holocene has contributed to the reduction of habitat. Since the species is long-lived, reproduces slowly, takes several years to reach maturity, and had a large range that has drastically contracted in comparatively few generations, inbreeding depression is a significant problem. The recovery efforts are hampered especially by low fertility of the remaining birds. Genetic analyses have been employed to select captive breeding stock in an effort to preserve the maximum genetic diversity.
Decline of Takahe
Takahē were assumed to be extinct but were rediscovered by Geoffrey Orbell near Lake Te Anau in the Murchison Mountains, South Island, New Zealand on 20 November 1948. Takahē were at one time present throughout this island country but for several reasons ceased to be found which made many think that they were wiped out. Many reasons were cited for the failure of this flightless bird. There are two significant periods in which Takahē numbers declined; Pre-European and Post-European arrival. Reasons for the Pre-European decline of Takahē were postulated by Williams (1962) and later supported in a detailed report by Mills et al. (1984). They held that climatic changes were principally accountable for the failure in Takahē prior to European settlement. The environmental variations before the European settlement were not suitable for Takahe which exterminated almost all of them. Survival in the altering temperature was virtually not tolerable by this group of birds. Takahē live in alpine grasslands but post-glacial era destroyed those zones which caused in intense declined their numbers. Secondly they suggested that the arrival of Polynesian settlers, about 800–1000 years ago, who brought dogs and Polynesian rats and hunted Takahē for food, started another decline. European settlement in the nineteenth century almost wiped them out through hunting and the actions of introduced mammals such as deer which competed for food and predators (eg stoats) which preyed on them directly.
Takahe population, conservation and protection
After long threats of extinction, Takahe now find protection in the Fiorland National park (New Zealand’s largest national park). Unfortunately, the species have not made a stable recovery in this habitat since they were rediscovered in 1948. In fact the takahe population was at 400 before it was reduced to 118 in 1982 due to competition with Fiorland domestic deer. Conservationists noticed the threat deer posed to takahe survival and the national park now implements deer control by hunting by helicopter.
The rediscovery of the takahe caused great public interest in which the New Zealand government took immediate action in closing off a remote part of the Fiorland National Park to prevent the bird from being bothered. However, since the moment of rediscovery, there were different perspectives on how the bird should be conserved. According to the Forest and Bird Society, takahes should be left to work out their own “destiny”. However, this viewpoint caused many to worry that the takahe would be incapable of making a comeback and thus become extinct like New Zealand’s native huia bird population. Interventionists then sought to relocate the takahe “island sanctuaries” and breed them in captivity. However, no action was taken for nearly a decade due to a lack of resources and the will to avoid conflict. Fortunately, biologists from the Department of Conservation utilized their experience of designing remote island sanctuaries to establish a safe habitat for the takahe on Maud Island in the Malborough Sounds, Mana, and Kapiti Island north of Wllington off the Wairarapa Coast, and Tiritiri Matangi Island in the Hauraki Gulf. When such conservation strategies such as translocation of a species to island sanctuaries are successful, populations generally reach their carrying capacity rather quickly which can subsequently generate numerous issues with productivity and “population growth rates associated with density-dependent effects as well as increased rates of inbreeding. “ Scientists discovered through the use of logistic regression and generalized linear models that the takage island metapopulation appears to have indeed reached carrying capacity as revealed by the increasing ratio of non-breeding to breeding adults, and recent declines in produced offspring. Such results pose problems regarding the maintenance of genetic diversity and thus takahe survival in the long term. Thus increasing translocation rates of takahe from the New Zealand mainland onto island sanctuaries may not be effective unless “surplus birds are removed”.
Future efforts for protection
An attempt for protection of the Takahe was done by “translocation to predator free island refuges”. This will ensure that more rails have a chance to try and reproduce and will not face difficulties while doing so. Also at these island refuges the Takahe have been receiving supplementary feeding in order to encourage the breeding between the rails. Various ideas have been proposed to protect the Takahe such as to enhance and expand the population and then eventually releasing them into the wild. Also to protect many want to artificially rear the birds so that the population continues to expand.
Many recovery strategies and goals, both long term and short term, have been set for the future. The general long term goals include “establishing a self sustaining” population of well over 500 rails and also to “establish free ranging populations on at least three predator-free islands” to have a suitable habitat as an” insurance” against death while in the wild. The third is the one of the most basic, but still crucial, it is promoting awareness of the extinction of the bird and how we should keep the population have a positive slope. This will be done by keeping a small number of birds in the view of the general public. The short term goals are much more specific, which includes maintaining the number of deer in the habitat which the Takahe live in and maximizing the number of egg manipulations and artificial bred rails. Also a short term goal is to create more islands that take care of the birds; these are the islands of Maud, Mana, Kapiti and Tiritiri and Matangi, which will have anywhere from 25 to 35 pairs of birds. It is extremely important to keep the Takahe population growing and take care of them otherwise they will once again go extinct and this time possibly forever.
- BirdLife International (2012). "Porphyrio hochstetteri". IUCN Red List of Threatened Species. Version 2012.1. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/106002929. Retrieved 16 July 2012.
- Trewick, S.A. & Worthy, T.H. (2001) Origins and prehistoric ecology of takahe based on morphometric, molecular, and fossil data. In: Lee, W.G.; Jamieson, I.G. (ed.), The Takahe: 50 years of conservation management and research, pp. 31-48. Otago University Press, Dunedin, New Zealand.
- UNEP-WCMC Species Page (April 2008)
- Taylor, Barry, Rails: A Guide to the Rails, Crakes, Gallinules and Coots of the World. Yale University Press (1998), ISBN 978-0-300-07758-2.
- del Hoyo, J. Elliott, A. & Sargatal, J. (editors). (1996) Handbook of the Birds of the World. Volume 3: Hoatzin to Auks. Lynx Edicions. ISBN 84-87334-20-2
- BirdLife International 2009. Species factsheet: Porphyrio hochstetteri. Downloaded on 1 December 2009.
- Williams, G.R. (1962) The Takahe (Notornis mantelli Owen 1848); a general survey. Trans. Royal Soc. New Zealannd 88:235-258.
- Mills, J.A. Lavers, R.B. & Lee, W.G. (1984) The Takahe: A relict of the Pleistocene grassland avifauna of New Zealand. New Zealand Journal of Ecology 7:57-70.