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New Zealand has a multiplicity of challenging animal-control problems, and all of them concern animals which man has intentionally introduced either for sport, food or fur. Since the beginning of European settlement in the 19th Century, approximately 53 species of mammals and 125 species of birds have been deliberately or accidentally introduced into New Zealand, and 34 birds and 31 mammals have become established (Wodzicki, 1950). The principal reasons the exotic big game animals (Riney, 1955), fur bearers and feral domestic livestock have been so destructive to certain habitats in New Zealand are because 1) some of the soils are highly susceptible to erosion, 2) the mountainous country often gets high intensity torrential rainfall, and 3) many of the endemic plants have little innate resistance to the heavy selective grazing or browsing pressure. The bulk of New Zealand's vegetation is composed of indigenous species. This unique flora must have evolved without the presence of browsing or grazing mammals, for New Zealand has no fossil or native land mammals, except two species of bats and a rat that was liberated a few centuries ago by the Polynesians. Consequently, natural selection did not have an opportunity to eliminate the highly palatable and non-browse-resistant plants in favor of those which were either browse-resistant or unpalatable to browsing mammals. As a result, some of the highly palatable indigenous vegetation in New Zealand is unable to withstand the heavy selective browsing and grazing pressure inflicted by the introduced mammals (Holloway, 1950, Howard MSa and MSb, Kean and Pracy, 1949, McKelvey, 1959, Riney et al., 1959, Wardle, 1961).