BLACKCAP 



parison with those produced by any other known species; 

 it is, in fact, difficult to conceive of more beautiful notes 

 being uttered. This development, which, is very remarkable, 

 must, in the light of this theory, have arisen from the greater 

 sensitiveness shown on the part of the females for the vocal 

 powers than for the colours of the males, and I do not think 

 that anyone will question this. We ought, therefore, to find 

 that during the courtship the males would utilise their power 

 of song to the best of their ability, but such is not the case. 

 As considerable significance is attached to this point, let 

 me repeat the facts which I have mentioned earlier when 

 describing the courtship. Until the females arrive the males 

 usually sing their true song, but occasionally, especially when 

 excited, imitate other species. Upon the arrival of the 

 females a change takes place, and excitement is at its 

 highest point, with the result that the true song is so 

 far forgotten that, especially during that part of the court- 

 ship when the male is close to the female, high-pitched 

 squealing notes, together with imitations, are almost solely 

 produced, and often for a considerable time without a pause. 

 Now let us see how the males behave under the influence 

 of a different kind of excitement. Eemove a young one from 

 the nest, when old enough to recognise and reply to its 

 parents, and notice the effect produced. The male approaches 

 within a few yards of you, twists and turns on the branches, 

 or flutters and flaps along the ground, uttering short snatches 

 of its song identically the same as when courting, but more 

 often squealing and imitating other species. Here, then, we 

 have a species which performs, not only during the period 

 of courtship, but also at other periods of excitement in its 

 life, a remarkable series of both bodily and, if I may use the 

 term, vocal antics. We cannot disregard these facts. If the 

 song has really been developed owing to the females showing 

 a greater preference for the males with the more highly 

 developed vocal powers, is it not a little curious that, dur- 

 ing the courtship, the true song should be so far forgotten 



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