Vertebrate Pest Conference Proceedings collection


Date of this Version

March 1972


New Zealand has been considered a classic among the world's natural laboratories where free-roaming wild mammals demand, and obtain, a rather overwhelming national attention. The enormous devastation by erosion processes is the consequence of intentionally introducing exotic species of mammals, for food, for sport and for fur. By its isolation in the Pacific, the flora of New Zealand evolved in the absence of a grazing and browsing fauna. There were no native mammals, save for the seals and two species of bats. The land has been the home of a most diverse fauna of flightless birds -kiwis, the giant moa, the rails, such as pukeko and kakapo, and flightless parrots. Many of its flighted bird species nest near the ground. It supports one of the oldest known reptiles - tuatara. The land, despite predominance of weak sedimentary and metamorphic rocks, has high and steep mountain ranges covered by dense forests and alpine grasslands. Torrential rain is characteristic of many mountainous regions. The flora exhibits a high rate - 60% - of endemism and exceptional incidence of polymorphism and hydridism. Briefly, the land has all the hallmarks of a delicately balanced array of evolutionary excesses made possible only by the absence of man and the absence of a fauna of browsing mammals in all the niches from mountain tops to the sea. Into this balanced order came Man. First, the Polynesians - the moa hunters, Morioris, during the 9-14th centuries, and the Maoris from that time - burned off the forests, exterminated the moas and initiated changes in the vegetation which are still only known in outline. Then, in the early 19th Century, European Man came and set about burning vast stretches of forest and the native grassland vegetation to make room for his sheep, cattle, goats and pigs. Somewhat later, when he had time for leisure and sport, he introduced the world's more popular game and fur—bearing animals. He introduced: Eight species of deer, the chamois and thar, the European hare (Lepus europaeus) and the European rabbit (O. cuniculus), the goat (Capra hircus) , six species of Australian wallabies, the brush-tailed opossum, the European hedgehog, rats and mice, birds - a long list of finches, Corvids, ducks and geese. All these have been added to the primitive landscape in the brief span of 130 years. The effects have been appalling: Scarcely a Forester, Hydrologist or Botanist visits the country without recording his utter dismay at the evidence of erosion, the havoc and dilapidation of the biota. Thus, accelerated erosion caused by the removal of the protective vegetative cover brings about extensive flooding of the lowland river plains where the country's principal industry, sheep and cattle farming, is carried out.