Preying on the Predators

Forest and Bird, Issue 299, 1 February 2001, Page 44

Preying on the Predators

JUDY GILBERT

reports on managing pests without

using poisons on Great Barrier Island.

howing the way to improving habitat for nature on private land is one of the inspirations behind Little Windy Hill, a restoration project on Great Barrier Island. The project also sets an example of how birds and plants can benefit without the use of poisons to control pests. The Little Windy Hill Company has a 230-hectare property on the southeastern coast of Great Barrier Island, bastion of the outer Hauraki Gulf. Windy Hill is a mosaic of inter-connecting ecosystems, including pohutukawa-clad cliffs and podocarp-broadleaf coastal forest, streams, small wetlands, and dry exposed areas of regenerating kanuka and manuka. There are populations of threatened kaka, kereru, and black petrel. Streams have native fish and freshwater crayfish, and there is good habitat for paua slugs and a variety of skinks and geckos. The company, made up of 15 individuals, purchased the land in 1972 with the goals of community and conservation. Over the years shareholders limited development in accordance with their ‘rural property management plan’ and covenanted 116 hectares with the QEII National Trust. The various forests continued to grow and regenerate, with fences kept stockproof, and recreational hunting of the feral goats and pigs. By the mid-1990s, however, it became clear well-intentioned passive conservation was not turning the tide for the waning biodiversity, declining populations of native birds being the most obvious indicator. In response, the company decided on a five-year ‘integrated pest management’ project focused

on actively managing plant, animal, and bird pests. The objective is ‘to sustain and enhance the biological diversity of the land through pest management, to increase bird life by reducing densities of pests predating on birds, and to nourish the dream of providing a new home for the declining numbers of mainland kiwi...’ The project was approved in October 1998 but it took six months to complete the tasks of finding funding — applying to WINZ Task Force Green for a subsidised field worker, sourcing equipment, selecting the area of land to be established as a ‘mainland island’, and networking for information. Since Great Barrier has no possums or mustelids (ferrets, stoats and weasels), feral cats and rodents are the primary competitors and predators. Advice was sought from the local Department of Conservation and the biosecurity unit of the Auckland Regional Council on the methods for trapping them. The project became operative in April 1999 with a Task Force Green field worker establishing tracks and traps in a 20-hectare valley of mature forest. The area was selected for its ease of access, good bird habitat, and as a suitable area to ‘cut ones teeth’ on pest management. The initial funding ($3000) was privately provided to get the project underway with the J.S. Watson Trust (administered by Forest and Bird) granting the first funding from an outside organisation. The local branch of Forest and Bird also provided funding for rat traps. Over the 18 months the project has been in operation the efficiency of tracks and trapping has improved with the field worker taking a trip to Te

Urewera to check out the ‘mainland island’ there. (See page 18 this issue.) Tracks are set at a maximum of 150 metres apart on the contours and traps at 25 metres spacing. Five different types of cat traps are established all around the perimeter, with around 200 metres between each trap. To date, 1600 rodents, 21 feral cats, 12 pigs, and 155 goats have been culled. Plant pests such as pampas, Mexican daisy, and cotoneaster have also been removed. Mynas and magpies are eradicated. The Windy Hill company has a philosophical commitment to managing pests without the use of poisons, and the effectiveness of this form of pest management is being followed with interest by local and central government agencies who are also keen to limit the toxic effect of poisons in the environment. From the outset, the company has been keen to monitor its progress to ensure that its objectives are achieved. Recently, the

Auckland Regional Council’s environmental initiatives fund paid for the first year of the Windy Hill ecological monitoring programme prepared by Dr Sam Ferreira, a DoC ecologist. The programme sets out over five years a comprehensive monitoring of forest-bird communities, seed and litter fall, seedling density, reptile and invertebrate communities. There are already indications of improved bird numbers in the mainland island area. The rodent data indicates a significant and sustained reduction in densities proving this is possible without the use of poisons. The company has been so encouraged by the success of the pest management that it will be extending the ‘mainland island’ area over the summer to about 100 hectares and has a second project on a neighbouring farm ready to begin a similar integrated pest-management programme. — Judy Gilbert supervises the Windy Hill project.