THE RELATIONS OF THE SEXES 165 



his moments of ecstasy he seizes a leaf or other object in his 

 beak, and with feathers on end and quivering wings chases 

 his mate in and out of the bower till both are tired ! The 

 Spotted Bower-birds provide a roof to this avenue, which may 

 be of considerable length, and confine their decorations almost 

 entirely to shells, which are often collected on the sea-shore 

 some miles away from the site of the bower. 



This, by the way, appears to be almost entirely constructed 

 by the males, though in all cases the females are believed to 

 assist. 



IV. Song and Instrumental Music 



It will scarcely be necessary in this place to dilate upon the 

 marvellous perfection to which some birds have attained in the 

 matter of song. The exquisite performances of the Skylark, 

 Nightingale, Blackcap, Thrush and Blackbird, and a dozen 

 others, must be known to all who will read these pages. 

 Rather, we are concerned here with the nature and purpose 

 of song among birds. 



It is commonly supposed that Passerine birds alone sing; 

 and further, that among these only those of sober-coloured 

 plumage are so gifted. Both these suppositions, however, have 

 no foundation in fact, though it is true the more brilliantly 

 coloured birds are rarely good songsters. But it is equally true 

 that a large proportion of dull-plumaged birds, even among the 

 Passerines, have no song, or at least can give forth but a short 

 musical refrain. No bird is absolutely mute, but some species 

 are extraordinarily silent, and at most give forth but mono- 

 syllabic sounds. 



No hard and fast line can be drawn between call-notes, 

 uttered to keep individuals or flocks together, or to give warning 

 of the approach of danger, and true song. Nor can any hard 

 and fast line be drawn between the times and occasions when 

 song is practised. 



In many cases it would seem to play a very important part 

 in courtship, the male seeking this means whereby to gain a 

 mate : but long after this important event has been accomplished, 

 singing is continued, apparently in sheer exuberance of spirits. 

 Some birds, on the other hand, sing but little after the courtship 

 is over. That song plays an important part in the task of 



