Back From Mainland Extinction After 80 Years

Forest and Bird, Issue 307, 1 February 2003, Page 9

Back From Mainland Extinction After 80 Years

POLLY STUPPLES

long plane flight and a environment does not appear to have quashed the mischievous nature of 30 buff weka, transferred from the Chatham Islands to Te Peka Karara (Stevenson’s) Island, in Lake Wanaka. In a closely monitored aviary, they tweak the tail feathers of their dozing neighbours, signal territorial boundaries with low-throated grunts, and chase each other away from the food bowls. The birds’ month-long confinement follows several years of negotiations, and the beginning of a far longer joint project between Ngai Tahu and the Department of Conservation, to restore the buff weka to the mainland. The buff weka Gallirallus australis australis is the palest of the four subspecies of weka. Formerly abundant in the drier eastern half of the South Island, they provided an important food source for southern Maori, as well as feathers and oil. They were taken to offshore islands by Maori and European settlers who also ate weka. By the late 1920s, a combination of habitat loss, and predation had taken its toll and buff weka became extinct on the mainland. The survival of the subspecies was dependent on just 12 birds that had been introduced to the Chatham Islands at the turn of the century. In that environment — free of stoats, weasels and ferrets — the birds thrived to the point now where an annual harvest of 5000 birds, from a population of around 60, 000, is permitted. Although the Chathams population is sizable, it is the only population of buff weka in New Zealand, and is therefore

regarded as vulnerable. Many previous attempts to restore weka to the mainland have been unsuccessful. The North Island weka is the ‘most translocated’ animal in New Zealand, yet many of those populations were wiped out through predation. DoC staff obviously hope that this project will be different. Putting the birds on a predator-free inland island offers some protection. Trapping will continue to pick up any strong-swimming pests invading from the lakeshore.

A ‘soft release method’ is aimed at encouraging the birds to set up territories on the island. Once they have established partnerships in the aviary, they will be released, pair by pair, and monitored with radio transmitters. Weka are able swimmers and, with their strong homing instinct, there is

concern that some birds may try to find their way back to the Chathams. DoC staff will kayak around the island to check that the signals are all coming from the right direction. The main threats to weka, when they leave the enclosure, will be people and fire. Te Peka Karara has long been popular

with boaties, but the rules have changed recently. Visitors are still welcome on the island but they cannot bring their dogs and they cannot light fires. Ongoing communication and education will be a major part of the bird minders’ job.