EVOLUTION OF BIRD-SONG 



supreme impulse and passion of the singer. Perhaps 

 the surroundings of the bird increase this effect. 

 The murmur of a stream ; the soft moonlight which 

 sometimes bathes the dewy meadows, and sheds 

 white waves across the road or the woodland track, 

 chequered with shadows of clustering fresh May 

 leaves these are suitable features in the realm of 

 this monarch of song, and increase his effects. Now 

 he prolongs his repetitions till the wood rings. 

 Now his note seems as soft as a kiss ; now it is 

 a loud shout, perchance a threat (rrrrrr) ; now a 

 soft peeuu, peeuu, swelled in an amazing crescendo. 

 Now he imitates the sip sip sip sisisisisi of the wood- 

 warbler, now the bubbling notes of the nuthatch. 

 The scientific investigator is abashed by this tem- 

 pestuous song, this wild melody, the triumph-song 

 of Nature herself, piercing beyond the ear, right to 

 the heart of the listener. He is pleading now ! But 

 no, he is declamatory ; now weird, now fierce ; 

 triumphant ; half-merry : one seems to hear him 

 chuckle, mock, and defy in almost the same breath. 



MIMICRY OF THE MARSH-WARBLER 



In The Zoologist for August 1892 is a graphic 

 account of the mimicry displayed by this bird, 



