152 Davey, Upsetting the Balance oj Nature i [vd.'x'xxiil. 



their food supply. They are destroying some of our native 

 birds by nesting in hollows formerly occupied by them. Even 

 the Laughing Kingfisher is menaced, and this in spite of its 

 being protected by Act of Parliament. Several instances of 

 this kind have come under my notice. This is strange, as the 

 Kingfisher is a much more powerful bird than the Starling. 

 The reason for its giving w^ay to the Starling is, I think, owing 

 to the fact that it never had to struggle and fight for a nesting- 

 place in the same way as the old-world Starlings have had to 

 do for many generations, and when the Kingfisher finds its 

 favourite nesting-spout in a gum tree occupied by a pair of 

 Starlings it merely looks for another hollow, and, on finding 

 this also occupied, searches again, until finally the hen bird 

 has to put up with a poor substitute, or possibly has to lay 

 her eggs before she can find a suitable place. This struggle 

 between the imported and the native fauna goes on right down 

 the line even to the earthworms, the imported worm being now 

 very common around Melbourne. 



The introduction of the Common Perch was a very serious 

 mistake, and one w^hich it is now impossible to remedy. The 

 introduction of trout of different species was bad enough as 

 regards the Blackfish, but, fortunately for these, the trout has 

 to be bred artificially, and when liberated finds many of our 

 streams unsuitable owing to their muddy bottoms, and also 

 that, during the warm months, the water rises in temperature 

 to a degree that in man 5^ streams proves fatal to them. 

 Although this fish will help to exterminate the Blackfish, I 

 doubt if it can do any harm after the extermination of the 

 former species. 



The great menace by the Perch is, 1 am afraid, to the so-called 

 Murray Cod. The Murray River and its tributaries now abound 

 with the Common Perch, and, owing to thfe enormous food 

 supply in these rivers, this fish will grow very rapidly. As a 

 result of this rapid growth, the number of eggs laid by it will 

 be enormously increased. This fish, where the food supply is 

 abundant, seldom feeds on its own species. Consequently, 

 there will be practically no check on its increase, and, as it is 

 a faster swimming fish than the Cod, the latter, when young, 

 will merely serve as food for it. Large Cod cannot capture it, 

 owing to its greater swiftness in the water ; therefore it may 

 be only a question of time when the Cod that is too large to be 

 swallowed by the perch will either l)e hooked, netted, or die 

 of old age, and if hi the meantime its young are devoured 

 when small it is obvious that the extinction of this fine fish 

 in Victorian waters is not very far distant. Even if the Perch 

 never touched a Cod it would still be a menace to this and other 

 native fish, o\\ing to its great fecundity, as a fish half a pound 



