Rare Takahe or Notornis (New Zealand)
The (South Island) Takahē or Notornis (Porphyrio hochstetteri) is a rare flightless bird indigenous to New Zealand. This unique bird, - the largest living member of the rail family (Rallidae) -, was once thought to be extinct. There were only 4 recorded sightings of Takahē between 1800 and 1898 and then none were seen until 1948 when, after a carefully planned search effort, a few pairs were rediscovered by Geoffrey Orbell near Lake Te Anau in alpine grasslands in the Murchison Mountains, South Island. The species have not made a stable recovery in this habitat since they were rediscovered. A related species, the North Island takahē (P. mantelli) or Mōho is extinct and only known from skeletal remains.
The Takahē is a stocky, sedentary bird with a massive red beak, pink stout legs and reduced wings. The colour of an adult is mainly purple-blue with a greenish back and inner wings. It has a red frontal shield and red-based pink bill. The Takahē overall length averages 63 cm and its average weight is about 2.7 kg in males and 2.3 kg in females. The standing height is around 50 cm. Sexes are similar, the females being slightly smaller.
The Takahē is 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 is monogamous (with pairs remaining from 12 years to, probably, their entire lives), builds a bulky nest under bushes and scrub, and lays one to three buff eggs. The chick survival rate is 73-97%. Recently, human intervention has been required to maintain their breeding success. The success of fledgling 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.
MAJOR FACTORS IN THE DECLINE OF TAKAHĒ
The near-extinction of the formerly widespread Takahē is due to a number of factors: over-hunting, loss of habitat and introduced mammals have all played a part. One suggested reason for decline is that the environmental variations before the European settlement were not suitable for takahē, and exterminated almost all of them. Survival in the altering temperature was not tolerable by this group of birds. Takahē live in alpine grasslands, but the post-glacial era destroyed those zones which caused an intense decline in their numbers. The spread of the forests in post-glacial Pleistocene-Holocene has contributed to the reduction of habitat. Also the arrival of Polynesian settlers, about 800-1000 years ago, who brought dogs and Polynesian rats and hunted Takahē for food, has started a significant decline in their numbers. In addition, European settlement in the 19th century almost wiped them out through hunting and the actions of introduced mammals such as red deer (Cervus elaphus) which competed for food and predators such as stoats (Mustela erminea).
EFFORTS FOR PROTECTION
The original recovery strategies and goals set in the early 1980s, both long-term and short-term, are now well under way. One of the original long-term goals was to establish a self-sustaining population of well over 500 Takahē. The population stood at 263 at the beginning of 2013, showing a slow but steady growth over the previous few years.
In the wild the species is still present at the location where it was rediscovered. Small numbers have been successfully translocated to 5 predator-free offshore islands, where the birds also receive supplementary feeding. The Takahē island meta-population appears to have reached carrying capacity as revealed by the increasing ratio of non-breeding to breeding adults, and declines in produced offspring. Such results pose problems regarding the maintenance of genetic diversity and thus Takahē survival in the long term. Thus increasing translocation rates of Takahē from the New Zealand mainland onto island sanctuaries may not be effective unless “surplus birds are removed”.
The Department of Conservation (DOC) runs a captive breeding and rearing programme at the Burwood Breeding Centre near Te Anau. Chicks are reared with minimal human contact, being fed and brooded through the use of puppets and models. The offspring of the captive birds are used for new island releases and to add to the wild population in the Murchison Mountains. The DOC also manages wild Takahē nests to boost the birds' recovery. Surplus eggs from wild nests are taken to the Burwood Breeding Centre.