INSTINCT AND INTELLIGENCE IN BIRDS 555 



What association seems to do for the young bird in the first instance 

 is to eliminate a lot of useless reactions, by limiting its responses to 

 those which count, for the amount of energy which goes to waste in 

 this direction, especially up to the time of the later manifestations of 

 fear, near the close of nest-life, must be very great. The pleasure 

 of getting the food seems to lead to an association with the nest itself, 

 the place where the food is received, and with the parent, the active 

 agent, together with her calls and the vibrations of the nest or branches 

 which attend her visits. Association with the nest seems to be strong- 

 est, for nestlings up to a late period respond freely to the call-notes of 

 other birds, which happen to pass near, to sudden gusts of wind, at an 

 early period especially, and to violent sounds of every description, like 

 the distant whistle of a locomotive. A more curious sight, which illus- 

 trates the indefinite character of this association, is often witnessed 

 up to the very last days of nest-life in many, if not all, of the common 

 altricious birds of the country. Not only does the casual excitement 

 of one bird arouse all the others into action, when, as it were, " the pot 

 begins to boil," and then subsides, but the nestlings often respond to 

 one of their mates, precisely as to the parent, for which it is plainly 

 mistaken, crowding eagerly around it begging to be fed, and in their 

 vain attempts to nestle under it, almost pitching it out of the nest. 



In early nest-life, any sudden jarring of the nest or the branches 

 about it will elicit the food-response as readily as when the vibration 

 is imparted by the touch of the parental foot, but discrimination comes 

 in this direction also, at any rate in certain species or individuals, and 

 is often well-nigh perfect at the advent of the instinct of fear. 



VI 



The acquired habits or tendencies which have been described may 

 in time become very uniform and more or less " stereotyped," but they 

 are widely different from those instinctive characters which alone are 

 inherited. 



We have been obliged to speak frequently of fear, which in its 

 origin must be regarded as an instinct in birds. It should not be for- 

 gotten, however, that if very young animals of any kind are separated 

 from their parents, so that their natural environments and experiences 

 are changed, we may look for a modification of this instinct, both as to 

 the degree and manner of its expression, and as to the time of its 

 appearance. In all the common altricious birds fear, in its later stages, 

 is attuned with the instinct of flight, or, as in the case of the cuckoo, 

 with the power of helping itself by entry upon a climbing stage, when 

 seven days old. In a cedar waxwing, on the contrary, it is not well ma- 

 tured until the thirteenth or fourteenth day, when the entire brood, 

 standing on their nests with heads upturned, suggest a gun, loaded, 



