BKIT1SH WARBLERS 



in the dim morning light of a stoat-like animal crawling 

 along the branches. This habit, whatever the origin, seems 

 now to be an indispensable part of the courtship and is 

 very strongly implanted in the male ; for, before following 

 the female, the leaf or piece of grass is searched for with 

 impatience, as the female does not stop but calmly pursues 

 her way, the result being that whatever he first gets hold of, 

 and can conveniently carry, is sufficient for his purpose. 



In referring to this period of the bird's life, I have used 

 the simple term " courtship" instead of the usual display 

 followed by selection. Fascinated by a picturesque theory, 

 I have, previous to this, attempted to interpret facts accord- 

 ingly instead of being ad utrumque paratios, but closer study, 

 devoted for some years to this courtship, convinces me that 

 sexual selection as a rational explanation of the phenomena is 

 impossible : the following reasons have been mainly instru- 

 mental in forcing this conclusion upon me. 



Selection is impossible unless there are two or 



more males to be selected from. 

 I can find no evidence of this being a general rule . in 

 Nature, for although a second male occasionally approaches 

 the zone of courtship and is consequently chased away by the 

 first male, yet he is in no sense a rival, making no attempt to 

 perform in the same extravagant manner ; and if these two 

 males were in competition for the female, and if such com- 

 petition were to be decided solely by her choice, then, not only 

 ought they both to display their plumage, but, unless the 

 female is to be credited with sufficient mental power to enable 

 her to carry, for her further consideration, the varying 

 characteristics of each male in her mind, such display ought to 

 take place simultaneously. 



" If the male assumes these attitudes in order that 



the female may see him to the best advantage and thus 



be enabled to make her choice, then she ought to be 



watching him when thus occupied." 

 This is by no means the case, for she is generally walking, 



14 



