MARSH WARBLER 



of a jerk. On these occasions the song may gradually become 

 more and more feeble until it develops into a quiet warble, 

 audible only a few yards away and much like that of the 

 Blackcap. Both sexes make use of a quiet note which is 

 evidently a call, as it is used constantly by one or the other 

 as they wander in search of food during periods of quiescence. 

 The male has yet another method of expressing his emotion, 

 which is peculiar and verges on the ludicrous. It generally 

 occurs after he has been absent from the female for a time. 

 Flying rapidly towards her and settling beside her, he con- 

 centrates all his efforts in violently producing a few bars of 

 his song, and whilst doing so sways his body from side to side 

 with his feathers tightly compressed, his bill pointing upward 

 and widely opened, and his neck considerably stretched. A 

 great part — perhaps the greater part — of the time which the 

 male and female spend in close companionship is a tranquil 

 one. It must not be supposed that the whole of the period 

 of sexual actrvity, or even that the first few days of that 

 period, is one of constant excitement. So far is this from 

 being the case that if it were possible to estimate correctly 

 the aggregate time during which emotional behaviour 

 dominated the situation, it would be found to form but a 

 very small part of the routine of their daily life. The out- 

 bursts of emotion are short, spasmodic, and irregular in 

 occurrence, rather than constant or even prolonged ; and it is 

 difficult to say in which sex they are first aroused. Much, if 

 not all, depends, I believe, upon the female in such matters. 

 She is, so to speak, the medium by which Nature prevents 

 a too liberal yielding to the sexual impulse ; not, however, 

 through the instrumentality of coyness, as suggested by 

 Professor Groos, but rather by the aid of some physiological 

 disposition which controls the sexual emotion. One sees the 

 male approach the female in a manner which makes his 

 intentions clear, and one sees her face him with lowered 

 head and feathers erected, an attitude which makes her 

 intention equally clear. One sees her, on the other hand, 



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