88 
The cause of the rapid disappearance in New Zealand of some species of birds, and absolute 
extinction of others, is a very interesting question, and I have already called attention to it in 
various published papers. In a newly colonized country, where the old fauna and flora are being 
invaded by a host of foreign immigrants, various natural agencies are brought into play to check 
the progress of the indigenous species, and to supplant them by new and more enduring forms, 
more especially in the case of insular areas of comparatively small extent. These agencies are 
often too subtle in their operation to arrest the notice of the ordinary observer ; and it is only the 
ultimate results that command his attention and wonder. But in New Zealand some special 
cause, apart from this general law, must be assigned for the alarmingly rapid decrease of many 
of the indigenous birds: in the course of a very few years, species formerly common in every 
grove have become so scarce throughout the country as to threaten to become extinct at no very 
distant date. 
Various reasons have been suggested to account for this. The natives believe that the 
imported bee, which has become naturalized in the woods, is displacing the Korimako, Tui, and 
other honey-eating birds. One of the oldest settlers in the Hokianga district (the late Judge Mailing), 
speaking to me on this subject, said “ I remember the time, not very long ago, when the Maori 
lads would come out of the woods with hundreds of Korimakos hung around them in strings ; now 
one scarcely ever hears the bird : formerly they swarmed in the northern woods by thousands ; now 
they are well nigh extinct.” On asking him his opinion as to the cause of this, he told me that he 
agreed with the Maoris, that the bee, having taken possession of the woods, had driven the honey- 
eatino- birds away from the flowers, and practically starved them out ; and he referred to the scarcity 
of the Tui, another honey-eater, in support of this view *. But it must be remembered that both of 
these species subsist largely on berries and insects, and that the comparative failure of their honey- 
food even if granted, will not of itself account for the rapid decrease of these birds ; while, on the 
other hand, the Totoara ( Miro australis) and other species which do not sip flowers are becoming 
equally scarce. It appears to me that the honey-bee theory is quite insufficient to meet the case, 
and that we must look further for the real cause. As the result of long observation, I have come to 
the conclusion that, apart from the effects produced by a gradual change in the physical conditions 
of the country, the chief agent in this rapid destruction of certain species of native birds is the 
introduced rat. This cosmopolitan pest swarms through every part of the country, and nothing 
escapes its voracity f . It is very abundant in all our woods, and the wonder rather is that any of 
our insessorial birds are able to rear their broods in safety. Species that nest in hollow trees, or in 
other situations accessible to the ravages of this little thief, are found to be decreasing, while other 
species whose nests are, as a rule, more favourably placed, continue to exist in undiminished numbers. 
As examples of this latter class, I may instance the Kingfisher, which usually scoops out a hole for 
* In this connection it is worth mentioning that on the Great Barrier and Island of Kawau, from both of which the 
Korimako has now disappeared, bees are plentiful; whereas on the Little Barrier and the Chickens, where the bird still lingers, 
there are no bees. 
t In a letter which I had the pleasure of receiving from the Rev. T. Chapman, of Rotorua, some years ago, that gentleman 
states:— “Wild Ducks were particularly numerous in this district on my arrival hero : you saw them by dozens ; you hardly 
see them now by twos. I have no doubt we owe this to the Norway rat. There is a place on the Waikato river, some twenty 
miles below Taupo, where the chiefs occasionally assembled to act out two important matters,— to discuss politics and eat kouras 
(crayfish). A few years after the Norway rat fully appeared, the kouras were no longer plentiful; and as the New Testament 
made Maori politics rather unnecessary, the usage of meeting no longer exists. The natives assured me that the Norway 
rat caught the crayfish by diving. Rowing up the rivers you see little deposits of shells : upon inquiry I found they were the 
selections of the Norway rats, who, by diving for these freshwater pipis, provide a Tcinalci (relish) for their vegetable suppers.” 
Herr F. von Fischer (Zool. Gart. 1872, p. 125) calculates that a single pair of these rats might have, after ten years, a progeny 
of 48,319,698,843,030,344,720 individuals. 
