NOTES 

 A CASE OF INSTINCT 



A young sparrow hawk fell out of its nest in the broken corn- 

 ice of one of the college buildings and was brought to my office. 

 I took it home and put it in a wire cage, set on a large stone at 

 one side of the lawn, where it remained for two months. The 

 first meal I gave it was of fish worms which I dropped into 

 its mouth. The second day I fed it cooked liver cut into small 

 bits, which I placed in its mouth. On the third day I placed a 

 piece of roast beef half the size of an egg on the bottom of the 

 cage. The hawk looked somewhat cautiously and then thrust 

 out one foot and grabbed the meat, viciously sinking his claws 

 into it. Its feathers ruffled, it spread its wings and fluttered 

 about the cage still holding the piece of meat which it con- 

 tinued to strike with its bill, its other foot and its wings. With 

 its outstretched wings, its curved back, its ruffled feathers and 

 its savage thrusts with beak and claw, it seemed a much more 

 formidable creature than it had when swinging on the swing a 

 moment before. The transformation from the sleek, handsome, 

 open-eyed bird to the infuriated beast was so sudden and com- 

 plete as to be really startling. One could well imagine that 

 such behavior would be effective in intimidating any small 

 creature such as mouse or bird that might be so unfortunate 

 as to fall its prey. Under the circumstances it seemed quite 

 useless behavior in view of the already docile character of the 

 roast beef. 



I continued to feed the hawk on some form of cooked meat 

 and the food always elicited the same sort of behavior. The 

 extent of the demonstration seemed to depend somewhat on 

 the hunger of the bird and the size of the piece of meat, great 

 hunger and a large piece producing the more exaggerated 

 behavior. 



Since the hawk was evidently too young to fly when brought 

 to me, it seems improbable that it had ever killed any animal 

 or that it had ever witnessed such killing. If this is true we 

 have here a clear case of the congenital tendency to kill prey. 

 Whether one could analyze the hawk's behavior into that con- 

 cerned directly with the act of killing and in addition certain 



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