ADAPTATIONS 421 



the extraordinary bill of this bird seems to have its use, and 

 we may easily conceive that the Black Cockatoos have main- 

 tained themselves in competition with their more active and 

 more numerous white allies, by their power of existing on a 

 kind of food which no other bird is able to extract from its 

 stony shell." 



Other instances of this competition are to be had in plenty 

 among the Parrots. The large bills of the Hyacinthine Macaws 

 (Ara hyacinthinus) of Central Brazil, like the beak of the Black 

 Cockatoo, are used for breaking open hard nuts, in the present 

 case palm-nuts, the shells of which are so dense as to be difficult 

 to break with a heavy hammer, yet they are said to be crushed 

 by the beaks of these birds. Thus then the beaks of these 

 Parrots recall the marvellous crushing power of the jaws of the 

 hyaena, which in strength exceed those of the lion. 



Again some Parrots, such as the Banksian Cockatoo {Calap- 

 torhynchus banksii) and those of the Genus Platycercus live 

 largely on insect larvae. The slender-billed Cockatoo {Lich- 

 metis nasica) of Australia, differs from that of other Parrots in 

 that the upper jaw is long, slender and only slightly decurved ; 

 and this modification enables the bird to dig for grass roots and 

 bulbs. Now it is instructive to note that a very similar modi- 

 fication of the beak has taken place in a Parrot restricted to 

 Chili — the slight-billed Paroquet {Henicognathus leptorhynchus) — 

 and this bird also lives mainly on grass roots. This being so, it 

 seems strange that the Owl-parrot or Kakapo {Stringops) of 

 New Zealand, which also feeds largely on grass, should have a 

 normal Parrot's beak. But this habit may have been recently 

 adopted, and it is certainly true that the diet of this strange 

 bird is supplemented to a very considerable extent by fruits 

 and seeds. When eating grass it is said to nibble after the 

 fashion of a rabbit, and for such a method of trituration the 

 more normal beak is admirably adapted. 



The large family of the Lories and some other Parrots live 

 almost exclusively on insects and honey, and for this purpose 

 have developed a quite peculiar tongue, described on p. 429. 

 Professor Moseley, writing of the little Swainson's Paroquet, 

 remarks that it " gathers so much honey from the flowers, that 

 it fairly pours out of the bird's beak when it falls shot to the 

 ground ". 



