WOOD WARBLER 



powers with unwearying zeal hour after hour, he now contents 

 himself with spasmodic outbursts, slovenly executed, a peculi- 

 arity which he shares with certain other species. If the 

 arrival of a female were in a preponderating number of cases 

 coincident with a complete cessation of the song, some 

 difficulties that lie in the path of an interpretation of the 

 latter would be cleared away, but unhappily this is not quite 

 an accurate statement of the facts. That a definite change in 

 the song does occur is obvious, a change so pronounced that 

 we can rely upon it as an indication of her presence. The 

 female, though she has no song, is strikingly persistent in 

 uttering her call note, which, loud and clear as it may be, is 

 often difficult enough to locate. Of course she remains more 

 or less within the confines of his territory, but at first 

 not absolutely so, for she may wander into an adjoining 

 one, and thus cause some confusion. The small plot of 

 ground which by force of habit has come to be regarded 

 by him as a headquarters is not necessarily sacred to her; 

 as likely as not she may select for her nest a corner of the 

 territory far removed from this particular spot, or even before 

 the question of a nesting site has become a practical problem 

 she may remain in a part of the territory some distance from 

 his headquarters, and this may lead to interesting behaviour 

 on his part. We have the headquarters on the one hand, ' 

 and the female on the other, the old influence and the new. 

 Now one would expect to find that the sexual instinct at this 

 particular time would be sufficiently strong to dominate every 

 other influence, but anxious as he is to approach her, he 

 nevertheless seems unwilling at times, even for her sake, to 

 desert his headquarters; to and fro he flies, following and 

 playing with her in one corner, then returning for a while to 

 his special group of trees, where, despite her appeals, he shows 

 anxiety — in fact seems almost compelled to resign himself to 

 his former habit. So here we have a piece of behaviour which, 

 though apparently trifling, yields nevertheless by slow 

 degrees only to the most potent of all instincts, the sexual. 



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