Community Care for Kiwi

Forest and Bird, Issue 302, 1 November 2001, Page 14

Community Care for Kiwi

SARAH GIBBS

SARAH GIBBS

reports that lessons from a ‘mainland island’

are helping people save kiwi in Northland.

he shrill call of a male kiwi pierces the dark night. Before he has even finished calling, his question is answered by the low, husky call of his female partner. Their raucous duet prompts a morepork and two more kiwi in a neighbouring territory to start up in competition. Standing in the dark listening to the eerie sounds of a threatened species being saved from extinction on the mainland is a somewhat surreal experience. It’s a sound that is fading rapidly from New Zealand forests, as stoats, weasels, ferrets, cats and stray dogs systematically decimate kiwi populations nationwide. But it’s also a sound that, thanks to places such as Trounson Kauri Park in

Northland, we now know how to bring back. Trounson, north of Dargaville, is one of six experimental ‘mainland islands’ run by the Department of Conservation. These are key sites where models of pest and predator control are developed. One of the challenges at Trounson was to establish what was necessary to get predator numbers low enough so young kiwi chicks were able to survive their first year. Scientists have calculated that around 20 percent of kiwi chicks need to survive in order for kiwi populations to maintain themselves. The fact that less than five percent of wild kiwi manage to live to breeding age is the main reason the birds are now considered an

endangered species. For the first two years of intensive pest management at Trounson, predators were trapped around the perimeter of the forest. In terms of results, the perimeter trapping worked well. Kiwi chick survival in those first two years alone increased to as high as 30 percent. To see if survival could be boosted even higher, an additional trap line was set up through the forest itself, and the second outer perimeter boundary of traps was also increased. The end result is kiwi chick survival rates of up to 85 percent, well worth the effort for those involved. Predator control at Trounson is now at the end of its fifth year. Since it began, more than 300 cats, 200 stoats and well in excess of 1000 hedgehogs have been removed. The sheer numbers of these predators show the extent of the problem in New Zealand. It also shows that it is possible to do something about it. Kiwi at Trounson are now doing well. More than 200 birds have been banded in the park — a healthy population given that the park is only 450 hectares. Indications are Trounson is filling up. Monitoring reveals that seven juvenile birds have left the safety of the park, possibly seeking new ground, with some birds travelling to nearby Waipoua Kauri Forest. The resulting control of possums and rodents is also clearly seen at Trounson, with the forest looking really healthy and increased numbers of birds in the park. New Zealand pigeon have been particularly noticeable, with flocks of up to 20 birds, giving us a small feeling for past times: William Swainson observed, in the 1860s, pigeon ‘flew literally in their thousands’. The research and monitoring components of experimental ‘mainland islands’ make places like Trounson relatively expensive to run. The development of the ‘mainland island’ concept has, however, allowed New Zealand to progress past the era where the only way to save endangered species is to bundle them onto offshore islands where they are safe from the predators that ravage the mainland. The pest-control techniques developed in ‘mainland islands’ can now be used around the country to ensure that we are not the last generation of New Zealanders who can listen to kiwi singing duets in the night forest.

Forest and Bird field officer

wrote her M.Sc thesis on the kiwi of Trounson.