AND INTRODUCED FAUNAS 513 



in which its larva used to bore. But it has now learned to bore into 

 certain introduced plants, and I have received from Mr W. W. Smith 

 of New Plymouth, specimens of oak trees {Quercus robur var. pedun- 

 culata), and of lilac {Syringa vulgaris) very freely turmelled by these 

 large grubs. 



Changes in introduced Fauna since Naturalisation 



In the introduction to this chapter I stated that the observations 

 of naturalists thirty or forty years ago led to the prevalent belief 

 that in this new country variation would proceed very rapidly among 

 introduced species of animals and plants owing to the removal or 

 rather absence of those checks which acted upon the species in their 

 native habitats. After nearly fifty years of fairly close observation I 

 have to state very definitely that such a belief has been absolutely 

 dissipated. / am aware of no definite permanent change in any intro- 

 duced species. 



For a long time I collected all the information I could lay my 

 hands on as to albinism in birds, expecting to find that it was greatly 

 on the increase. Buller referring to this matter says : 



A remarkable feature in the New Zealand avifauna is the inherent ten- 

 dency to albinism. The condition itself is no doubt due to the absence of 

 colouring pigment in the feathers; but the difficulty is to find any suffi- 

 cient cause for this in a temperate climate like that of New Zealand. In 

 India, as is well known, the tendency 'is in the opposite direction, melanism 

 being of very frequent occurrence. Strange to say, there is the same 

 tendency to albinism in the imported birds. Albino sparrows are /ar more 

 common than they are in their native country, and even the skylark not 

 unfrequently changes its sober dress for a yellowish-white one. 



The itaUcs are mine, but the statement shows that Buller — ^writing 

 nearly fifty years ago — ^was of opinion that colour changes were 

 rapidly taking place. 



Writing in 1891 I said: 



Among house sparrows in particular, variation in colour and especially 

 development of white feathers is extremely common, and is certainly on 

 the increase. From evidence I have collected in Otago, I find that the 

 development of white plumage, usually in the wings and tail, is a very 

 common feature, and by no means confined to sparrows. I have numerous 

 recorded cases of the occurrence of more or less complete albinism, as 

 well as of the development of bright colours in thrushes, blackbirds, 

 linnets, skylarks and starlings. Such variations are, of course, not un- 

 common in the original habitats of all these birds, but it never tends to 

 increase. Here, on the other hand, it is of frequent occurrence, and seems 

 to me to be very decidedly on the increase. My own observations lead 

 me to think that birds with any bizarre or distinctly abnormal colouring 

 are wilder and more shy than their normally coloured fellows; but as 



T. N. z. 33 



