TRANSACTIONS OF SECTION D. 209 



(g.) On some Changes induced in the Indigenous Fauna 

 AND Flora by Introduced Plants and Animals. 



The influence exerted on the indigenous fauna and flora by 

 the advent of Europeans with the accompanying immigration 

 of foreign animals and plants has certainly been very remark- 

 able, and in some cases very destructive. The singular 

 example of the change of habit in the kea {Nestor notabilis) 

 has attracted a very large amount of attention just because 

 it is a very conspicuous case. But there are no doubt 

 numerous other exainples of the same alteration, to which 

 httle or no attention has been drawn. It is, however, extremely 

 difficult to distinguish between the changes caused by direct 

 human agency, especially by fire and firearms, and those due 

 to the imported animals and plants. The whole process of 

 settlement — the burning-down and clearing of the surface 

 vegetation, the ploughing of the land, and the draining of the 

 swamps — all this has brought about radical changes. By this 

 means not only have enormous numbers of indigenous plants 

 and animals been destroyed, but in the case of the latter 

 especially their food-supply and shelter have been removed, so 

 that they have more easily fallen a prey to their enemies. In 

 this way vast numbers of insects have disappeared entirely 

 from the settled districts : sandflies, for example, those pests 

 of the Sounds district, are now almost unknown on the east 

 coast of the South Island. The introduction of insectivorous 

 birds has greatly aided this process of extermination. To such 

 an extent has this work of alteration gone that in all the 

 thickly-settled parts of Otago and Canterbury the facies of the 

 fauna and flora is that of England, and not of New Zealand. 

 This disappearance of insects must greatly affect the native 

 flora. Thus, flies are the principal agents in effecting fertilisa- 

 tion of many of the indigenous flowering plants; but the native 

 forms of Diptera have in many cases become very rare, so that 

 these plants are probably now dependent on introduced flies 

 and bees, or escape fertilisation altogether. Many of the 

 coriaceous and hairy plants of these Islands probably acquired 

 these characteristics as a defence against the numerous grass- 

 hoppers and other phytophagous insects which used to abound 

 in the early days of settlement. But these insects are now 

 almost exterminated in many parts, while others with different 

 habits have taken their place, and were it not for the pre- 

 valence of fires these now protected plants would probably 

 increase to a very considerable extent, unless, indeed, the same 

 destructive agencies have served to exterminate the insects 

 which fertilise the flowers. 



Some plants appear to be dying out without the inter- 

 vention of fires. This is the case with regard to the spear- 

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