ANIMAL IMMIGRANTS IN NEW. ZEALAND.•
ONE does not need to be a biological expert ir; order to appreciate the merit and profound interest of the book which a veteran New Zealander naturalist, Mr. G. M. Thomson, has written on the many species of animals and plants which have been introduced into New Zealand since the islands were first visited by Captain Cook in 1769. In no other country can the problem of acclimatization be studied with such precision. New Zealand is separated from the nearest large country, Australia, by a turbulent ocean, half as wide as the Atlantic. The native fauna and flora are well known—the only mammals, for example, were the dog, rat and two kinds of bat—and the circumstances under which most, if not all, of the alien species were intro- duced are on record. New Zealand has had many enthusiasts who sought to acclimatize in their new land the animals and plants that they knew and loved in the old country. Mr. Thomson's book aims at being a comprehensive account, based on written evidence and on his own observations for half a century, of the varying fortunes of at least six hundred species of animals and of many species of plants which have been imported into New Zealand since Cook's day. Darwin, in writing The Origin of Species in 1859, foresaw that New Zealand would afford a test case. Apparently he was wrong in thinking that—apart from human intervention—the imported species would kill out many of the indigenous species. Further, we may note at once Mr. Thomson's remarkable conclusion that he knows of no definite permanent change in any introduced species, despite many earlier assertions to the contrary. The belief that New Zealand rabbits, for instance, would be like Joseph's coat, of many colours, appears to be unfounded.
Rabbits have been, of course, the most mischievous of all the animals brought into New Zealand. Mr. Thomson has found that rabbits were brought from Sydney before 1838, and that many persons, unconscious of the harm they were doing, imported rabbits into various districts. In the 'seventies the rabbits turned great areas of South Island, especially in Otago, into a desert, and for twenty years all efforts to check them were vain. The farmers put down poisoned grain and thus destroyed all the partridges and pheasants. The stoats and weasels introduced in large numbers to kill the rabbits also disposed of many of the native birds, though it is noted that some of the birds have learned how to kill stoats. But nature has come to the rescue. The rabbits, in many districts, multiplied beyond the capacity of the land to sustain them, became a prey to disease, and gradually declined in numbers. " Large areas of hill country in the wetter districts are now completely clear of rabbits," according to Mr. James Begg, of Mosgiel. Possibly the rich pastures which the rabbits spoiled will in time recover their old luxuriant vegetation. The first European animal to enter New Zealand, other than the ship's black rats, was probably the pig. Cook put some pigs ashore, and other British visitors gave pigs to the natives. The animals ran loose and were the progenitors of the wild pigs that abound in New Zealand. In some places them wild pigs attack sheep, espeCially young lambs ; they are also fond of young rabbits, which they dig out of the burrows. In the bush country, especially in the volcanic districts of North Island, there are wild horses, the descendants of stray animals, and there are many wild cattle. Various species of deer have been introduced from time to time and have, on the whole, done welL In the hill-country of North Island and in the Southern Alps the red deer—some from Windsor Park and some from the Ifighlands- have multiplied rapidly, so that deer-stalkers can probably get better sport in New Zealand than at home. Indeed, " the attraction of red deer shooting is now to be reckoned as one Of the assets of the country from a tourist's point of view." The fallow deer, the Sambur deer and the white-tailed or Virginian deer have also found the new conditions favourable. Eight chamois were imported in 1907, and these fine animals are now numerous in the Southern Alps. Some of the cats introduced by settlers took to hunting game, and there are now many wild cats—often so strong and fierce that no dog would tackle one single-handed. Packs of wild dogs, also the descendants of stray animals, were common some years ago bull have been • The Naturalization of Animal* and Plants in New Zealand. BY the Flom George M. Thomson. Cambridge : at the University Press. 142s. net.]
exterminated.— Hedgehogs were imported by a Christchurch -resident in 1894, and are now so plentiful as to be a pest to the poultry-farmers and gardeners.
The failures with imported birds have been more numerous than the successes. The familiar brown owl, pigeon, thrush, blackbird, rook, starling, chaffinch and house-sparrow, among others, appear to have established themselves, as well as the mallard and the Australian black swan. The partridge and pheasant have failed utterly, not so much because .they are attacked by hawks and ferrets as because the smaller birds eat up the insects on, which the larger birds mainly depend. Mr. Thomson notes that the thrush retains its old habits and commences to sing in May, though that is at the beginning of the New Zealand winter ; it breeds in September and October and usually breeds again later in the season. Starlings thrive greatly ; they aro said to have exterminated the grasshopper and other insects, but they are accused of ravaging the orchards, as in .Australia. The sparrow, like the rabbit, has proved a doubtful blessing, though in 1864 the Auckland Provincial Government was offering thirty shillings a pair for imported house-sparrows. Mr. Thomson is inclined to defend the sparrow against the angry farmer ; he admits, however, that New Zealand sparrows have an unpleasant habit of picking flowers to pieces—especially the spring flowers. Brown trout have been successfully naturalized in New Zealand waters ; but many attempts to introduce salmon have apparently had little or no result, for the young fish, after leaving the rivers for the sea, have failed to return. Mr. Thomson deals fully also with the many imported plants. The blackberry, we may note, has thriven all too well, so that it is now regarded as " the most noxious weed in New Zealand " and goats are kept to eat it down. On the other hand, the primrose and cowslip, when planted or sown in the bush or in the open, have failed to establish themselves. But we must leave Mr. Thomson's learned and fascinating book, which will become a classic of acclimatization.
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