54 BIRD BEHAVIOUR 



Australian region, where these otherwise universally 

 distributed birds are absent. 



The chief grub- eaters are the Black Cockatoos 

 (Calyptorhynchus) of Australia and the curious New 

 Zealand Parrots known as Kakas (Nestor) ; but the 

 habit is probably commoner than is supposed, since 

 most Parrots in captivity evince a liking for animal 

 food, although too much of this is bad for them, 

 often causing a skin-irritation and the adoption of 

 the feather-plucking habit: This, however, has 

 probably more to do with the want of exercise. 



It seems improbable that the Parrots should have 

 developed their extraordinary deep-curved bill, 

 unique among vertebrates in its hinged upper jaw 

 and extreme biting power, merely to feed on seeds 

 and fruit, and it is noteworthy that the Parrot 

 which has the least typical beak, Pesquet's Parrot 

 of New Guinea (Dasyptilus pesgueti), in which the 

 upper jaw at any rate is more like an Eagle's than 

 a Parrot's, tears at its food of fruit like a carnivorous 

 bird at flesh, and also has less Parrot-like movements 

 than the rest of its tribe, hopping from bough to 

 bough with a flicking action of the wings evidently 

 it has not fully attained the Parrot specialization in 

 form or action, and corresponds among the Parrots 

 to the Magpie-Goose among the Ducks. 



The White Cockatoos, which are generally 

 ground- feeders, use their bills much in digging up 

 bulbs and the egg-cases of locusts ; in the Long- 

 nosed Cockatoos (Licmetis), which are especially 

 addicted to a diet of roots, the upper bill is par- 



