262 BIRD BEHAVIOUR 



at a dealer's shop, a good talker in two languages 

 I was told, had become independent of the usual 

 head-scratching by human fingers, for it would 

 scratch its head itself with the swing in its cage, 

 grasping this with one foot as it stood on the perch 

 below, and moving it backwards and forwards over 

 its poll. 



The other bird I was told of when delivering a 

 course of lectures at Maidenhead some years ago ; 

 this would scratch its head with a piece of stick, 

 according to the account given me, and though 

 with the usual perversity of the species it refused 

 to perform in my presence, it did at any rate 

 condescend to take the stick proffered by its owner 

 in its foot and hold it a while. 



From my own experience I think I should rate 

 the great Salmon-crested Cockatoo of the Moluccas 

 (Cacatua moluccensis) as the most intelligent of 

 birds ; this will even make use of signs to intimate 

 its wishes, for when one approaches a Cockatoo of 

 this kind they are always tame, being presumably 

 hand-reared it will commence stroking its head 

 with its foot in an obvious invitation to " scratch 

 a poll " which is quite sincere, for I have never 

 known one abuse the confidence reposed in its tame- 

 ness. 



The only other Parrot I have seen make this 

 sign, and that more rarely, is the large Red-and-Blue 

 Macaw (Ara chloroptera), and this also is the only 

 bird I have seen smiling ; when so doing it extends 

 the upper bill straight forwards and draws back 



