400 Transactions. 



with the evidence of what we know of other cuckoos, make it certani that 

 Chalcococcyx lucidus is predatory. Mr. Potts (24) says, " The whistler is a 

 great insect-eater, and appears specially fond of the well-known ladybird. 

 We are not without certain suspicions that it devours or destroys the eggs 

 of other birds." 



Now, as to the other reason for the hatred of the birds generally — the 

 habit of coolly dropping its eggs into other birds' nests — of this the evidence 

 is overwhelming, though no one has as yet seen the act of deposition. The 

 riroriro {Pseudo-gerygone) has been known to actually hatch out this bird 

 from an egg which has been dropped into its little bag-like nest ; and the 

 monster thus hatched in many instances heaves out the occupants, or lies • 

 on top of them, so as to obtain possession of all food and thus starve them. 

 I have myself found young warblers alive on the ground beneath the nest 

 containing a young bronze cuckoo ; I have replaced the young warblers, 

 and found them dead on the ground next day. I also remember as a very 

 small boy being told that one of my brothers, now deceased, had actually 

 seen the process of expulsion going on, but I was too young to take any 

 interest in it. Now, why is the grey warbler the bird that is most frequently 

 selected as a host for this egg — the only bird in our country which builds a 

 domed or covered-in nest ? Many of you know Wallace's description (25) of 

 the feeding-area and the breeding-area of migratory birds. Now, in some 

 birds the summer breeding-area and the winter feeding-areas coincide — the 

 nature of the country is satisfactory, and the supply of food is available all 

 the year round ; in others the two areas are separated by more or less 

 wide intervals. New Zealand is the breeding-area, New Guinea probably 

 the feeding-area, of this cuckoo, and the construction of the nest of the riro- 

 riro leaves no doubt that it, too, in the remote past, came to this end of the 

 great continent to breed, still building its pendant nest, so difficult of access 

 to the various enemies — snakes, &c. — which it had to face in its tropical 

 feeding-area. In all tropical climates there are numbers of birds which 

 build pensile nests, adequately protecting their young, and it is significant 

 that the only other one of our birds which has a nest approaching in any 

 degree a pensile nature is the white-eye or Zosterops of tropical Australia. 

 The cuckoo chooses the nest of the warbler — first, because it is a bird that 

 almost certainly at one time had the same breeding and feeding areas ; 

 second, because the young hatched in such a pensile nest have more chance 

 of reaching maturity than when hatched elsewhere — eggs deposited in such a 

 nest are in comparative darkness, and are less likely to be disturbed, thrown 

 out, or deserted. Chicks reared in such a warm, comfortable home have a 

 great advantage over birds growing in open, uncovered nests. The proof 

 of these points can be seen in the preservation of the riroriro when so many 

 of our other little birds have almost disappeared. Sir Walter Buller (26) 

 gives an account of the warbler hatching out a young cuckoo, and has a 

 plate of the cuckoo in a warbler's nest ; and Potts (24) mentions sixteen 

 instances of cuckoos' eggs taken from the nest of the warbler. 



A correspondent had this season a cuckoo's egg and several eggs of the 

 warbler sent him through Magister's kind offices. These had been most 

 unfortunately removed from the nest instead of being watched for further 

 developments. There is no doubt that a number of young cuckoos of either 

 species are fed by other birds, and particularly by the grey warblers, which 

 have not necessarily hatched them at all. l)ut which, finding them piping 

 in distress, take pity on and feed the orphans. This is quite commonly 

 observed in Australia (22). Little birds which are never known to hatch 



