398 OUTLINES OF EVOLUTIONARY BIOLOGY 



once more exposed, by some unfortunate change in its environ- 

 ment, to the old struggle from which it had escaped. This has 

 actually taken place in the case of the flightless birds of New 

 Zealand and other remote islands. With the advent of Euro- 

 peans, predaceous mammals of many species dogs, cats, rats, 

 weasels, stoats and ferrets have been let loose upon their 

 helpless victims. These are once more exposed to a keen 

 struggle for existence, while at the same time they have lost 

 those very organs which are necessary to enable them to maintain 

 themselves in that struggle, and natural selection, having 

 regained her power, is rapidly exterminating them. It is not 

 too much. to say that in a few years' time there will be no 

 flightless birds left in New Zealand except in special reserves 

 where they are being protected by man. 



It is highly instructive in -this connection to contrast the con- 

 dition of such a bird as the flightless parrot, or kakapo, with that 

 of its relative the kea. The kakapo is a large, heavy bird of 

 nocturnal habits and with practically no means of defence ; it 

 haunts the dense forest and is rarely seen except when hunted 

 out by dogs. The kea, on the contrary, is one of the strongest 

 fliers of the parrot tribe. It frequents high and more or less 

 inaccessible mountain regions and since the advent of Europeans 

 has learnt to make use of the sheep which they have introduced 

 as an additional food supply. It is doubtful whether the utmost 

 efforts of the sheep farmers, who annually expend large sums of 

 money for the purpose, will ever enable them to exterminate the 

 kea, and it is equally doubtful whether the efforts of the New 

 Zealand Government to preserve the unique flightless birds will 

 suffice to" prevent the complete extermination of the kakapo 

 within the next few years. 



The aboriginal human population of remote islands has of 

 course suffered not less than the lower animals from the in- 

 vasion of their retreats by Europeans, although not always 

 exclusively at the hands of the Europeans themselves. There 

 are, perhaps, few more striking examples of the extermination of 

 a primitive native race than that afforded by the rapid disap- 

 pearance of the Moriori inhabitants of the Chatham Islands, 

 some four hundred miles to the east of New Zealand, during the 

 nineteenth century. 1 At the time of my visit to these islands, in 



1 Compare Dencly, " The Chatham Islands : A Study in Biology " (Memoirs and Pro- 

 ceedings of the Manchester Literary and Philosophical Society, Vol. XLVI., 19U2). 



