INSTINCT AND INTELLIGENCE IN BIRDS 



1 3 I 



Growth-records in Cedarbirds and Cuckoos, from Hatching to Flight, 



or Climbing Stages 



Cedarbird No. 4 was probably starved by its more vigorous mates, after the 



second day. Cuckoo No. 2 fell out of its nest. 



" " indicates the egg. 



cedar waxwing, and has based his results upon a much larger number 

 of cases. He also considers that the three stages enumerated correspond 

 to stages in the development of muscular coordination, of association 

 and the instinct of fear. During the first period, when the power of 

 motor coordination is weak, according to this observer, " the first crude 

 discriminations and associations are made," and the first signs of in- 

 stinctive fear noted. In the intermediate period (fourth to seventh 

 day), discrimination improves, and association is perfected, while from 

 the beginning of the last period " there is an abrupt change in all the 

 reactions, the food-reaction ceasing for all the artificial stimuli, except- 

 ing occasionally for the visual, and fear begins to develop rapidly 

 through several forms of manifestations." 



Kuhlmann recognizes five different manifestations of fear, begin- 

 ning with " cessation of the food-reaction to stimuli that at first aroused 

 it," and ending with " escape from the nest when approached." Dis- 

 crimination and the formation of associations between the food and 

 certain stimuli are thought to develop simultaneously, and " all stimuli 

 with which no pleasant associations are already formed are then at the 

 same time instinctively feared." The food-reaction is not only modified 

 by association, but is inhibited by fear, and while the development of 

 association is gradual, the passage of one manifestation of fear to the 

 next in order is often very abrupt. Such animals, he says, " come to 

 fear particular things not so much because of unpleasant associations 

 that are connected with them, as because the taming process has not 

 been completed." 



