INSTINCT AND INTELLIGENCE IN BIRDS 127 



responses are about as uniform and predictable as those of an electric 

 bell. Eemove the blind and naked cedarbird from its nest, and the 

 complex food-reaction is given as regularly and as continuously as 

 before (Fig. 26). By the second or third day, however, all this has 

 changed, and it is difficult to get any food-response if the bird be out 

 of its nest with which association has become established. If the young 

 are not removed, however, the feeding reaction is usually regularly 

 given, unless checked by satiety or the rise of the instinct of fear. 

 Association in the early life of young birds thus tends, as we have seen, 



Fig. 26. Young of Cedar Waxwing, blind and naked ; but little over twenty- 

 four hours old : a, typical prone position, when at rest ; b, typical food-reaction, or 

 reflex response to sound or contact-stimulus. 



to cut out a lot of useless reactions, and to limit their responses to those 

 which count. 



Growth in Relation to the Development of the Instincts and Intelli- 

 gence. — We have used the term " instinct " as synonymous with com- 

 pound reflexes, that is, as reflexes involving relatively complex coordi- 

 nations of the muscles and other organs. Although the sign or 

 manifestation of an instinct may be suddenly given, the instinct itself, 

 like every other power, seems to be unfolded gradually, and in correla- 

 tion with the organs upon which its action depends. 



• In many precocious birds, which run, swim or fly at birth or 

 shortly after, some of the instincts are relatively perfect at the moment 

 of emergence from the shell, or according to certain observers even be- 

 fore this event, as when the young, which remain for hours with the 

 shell chipped, are thought to respond instinctively to the warning 

 cries of their parents. In rare cases, as in certain megapodes, they are 

 born masters of their own destiny, and receive no care from parents 

 which they never see. At the other extreme stand the common altrices, 

 like the robin or cedarbird, which are blind at birth, and so helpless 



