Private individuals and acclimatisation societies have introduced over 130 species of birds, about 40 species of fish, and over 50 species of mammals into New Zealand. Of these only about 30 birds, about 10 species of fish, and about 30 mammals have become truly established in the wild. Among birds introduced were Australian bellbirds, cirl bunting, diamond sparrows, jager birds, Java doves, ortolans, Wonga pigeons, and Australian shrikes, to mention a few of the more unusual varieties. Brown and rainbow trout were established in this period, and various other species such as whitefish, alpine char, and Tahoe trout were introduced but failed to become established. All the mammals established in the wild in New Zealand, with the exception of domestic species, have increased to such an extent that protection has been removed from them because of damage done, and active steps have been taken to control them. The fur value of the opossum has been scant compensation for the damage caused to forests. Rats, cats, and dogs preyed on native birds and the introduction of stoats, ferrets, and weasels to prey on the rabbit swung the balance further against those species which had already become rare as a result of changed ecological conditions. These varied and numerous introductions produced a profound disturbance in the balance of nature, additional to the direct effects of settlement and development. Browsing and grazing animals modified the vegetation and it is now difficult to find vegetation which has not been modified to some degree. In many cases introduced birds competed for food and habitat with native birds. While there is no doubt that some introductions have been entirely beneficial and are valuable assets, whether as food, for sport, or for aesthetic values, other acclimatised animals have become major economic problems and have necessitated control measures. Acclimatisation societies were not responsible for the introduction of all the animals which subsequently became pests. The majority of introductions were carried out in a haphazard manner with little consideration of ultimate effects. Few people realised the potential dangers of indiscriminate importations. Private individuals, acclimatisation societies, and the Government all bear some responsibility for the more undesirable importations.