isms supercede it. He says, however, that ''Instinct . . . 

 could never lead a Summer Yellow-bird up to building- a two- 

 story nest to let a Cowbird's egg addle below." And also, on 

 the subject of a two-story nest, ''It argues as intelligent a de- 

 sign as was ever indicated in the erection of a building by a 

 human being. No question of iaherited tendency enters here; 

 and if it did, the issue would only be set back a step no nearer 

 determination, for there must have been an original double nest, 

 the result of an original idea." A different interpretation of 

 this behavior will be offered presently, but first let us note that 

 Coues' conception of an instinct differs very little from our own, 

 as radicated in the following words: "Such an 'instinct' is 

 merely force of habit, inherited or acquired — a sum of ten- 

 dencies operating unknomngly and uniformly upon the same 

 recurring circumstances, devoid of conscious design, lacking rec- 

 ognized prevision; totally inadequate to the requirements of the 

 special emergency." {Ihid., page 183). 



There need be no denial of the fact that the imposed-upon 

 birds often give signs of distress at the visit of the imposter 

 Gowbird. Similar signs of distress are shown, however, by prac- 

 tically all birds at the approach of an enemy. If their distress 

 could be subjected to analysis no doubt the emotions of fear and 

 anger would be prominent components. These emotions are 

 commonly and readily explained as instinctive. 



Suppose, now, that a Cowbird egg is deposited, and is found 

 by the rightful owners of the nest upon their return. The most 

 difficult problem of the case is now presented. Do the imposed- 

 upon birds recognize the egg as an object which wiU hatch into 

 a young bird larger than their own, and which will be detrimental 

 to their own offspring? Or do they simply recognize the egg as 

 a foreign body which does not belong in their nest ? Our answer 

 to this inquiry will, doubtless, point the way to the conclusion 

 as to instinctive or intelligent behavior in the case. 



Under one set of circumstances the Cowbird may have been 

 discovered at the nest of another bird ; the latter shows signs of 

 excitement and opposition to the presence of the Cowbird, Upon 

 the withdrawal of the Cowbird the exciting stimulus is removed 

 and the reactions cease. Such behavior may take place without 

 greater necessity of assuming intelligence than in the case of the 

 reactions of an amoeba. 



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