GENERAL CONSIDERATIONS 539 



lobster and the crab may yet be met with as permanent residents 

 of New Zealand waters. 



Other interesting problems in connection with introduced bird- 

 life in New Zealand are the partial migrations which take place, and 

 the extent to which certain species have succeeded or failed to estab- 

 lish themselves in various districts. These problems may be best 

 illustrated by taking specific examples. 



The Australian magpie (Gymnorhina leuconota) was introduced in 

 considerable numbers into Canterbury and Otago between the years 

 1865 and 1 87 1. In the latter district it seemed at first as if it were 

 going to become strongly established, for the birds began to build in 

 the neighbourhood of Dunedin, and as far south as Inch Clutha, 

 but for some unexplained reason they gradually disappeared com- 

 pletely. Meanwhile they throve in the neighbourhood of Christ- 

 church, especially to the south, and have since been gradually working 

 their way southwards. Within the last year or two (1918-19) they 

 have been reported as far south as Hampden and Moeraki. In the 

 North Island they are fairly common in certain parts, but Mr W. W. 

 Smith informs me that they are not so abundant now in Taranaki as 

 they were some years ago. No doubt the food supply, which varies 

 to a considerable extent according to the prevalence or scarcity of 

 other insect-eating birds, is a main cause of this partial migration, 

 but it is most difficult to arrive at the facts of the case. 



The minah (Acridotheres tristis) is another species which has 

 largely changed its location since the early days of its introduction, 

 only in this case the cause of its gradual disappearance from certain 

 districts is more directly traceable to its competition with the ubiqui- 

 tous starling. Minahs were introduced into all the main centres — 

 Auckland, Wellington, Nelson, Christchurch and Dunedin — in the 

 early seventies. They increased in all these localities for a time, but 

 as the starlings multiplied much more rapidly, the minahs either all 

 died out, or were driven away in the south. By 1890 there were none 

 left in Dunedin or its neighbourhood, only a few about Christchurch, 

 and none in Nelson. They have all but disappeared from Wellington, 

 and from the towns of Wanganui and New Plymouth, though they 

 are still common in the country districts of Taranaki, Manawatu, 

 Wairarapa and Hawke's Bay. 



The chaffinch {Fringilla coelebs) was introduced into all the main 

 centres in the early seventies. These birds are most abundant in 

 many parts now, but their occurrence in Otago has been most erratic. 

 A few years after their introduction they became fairly common and 

 then nearly disappeared. Probably the eating of poisoned grain was 

 the cause of the partial disappearance of these and other small birds, 



