INTRODUCTION. 13 



to keep them together. The lights of our great cities 

 often attract those aerial wanderers, and high up in the 

 air the cries of wild geese or swans, or the sharp whistle 

 of the Widgeon, may be heard by the dwellers below. 



" The red-throated Diver flies at a great height, and 

 may be heard uttering a distressing cry, like that of a 

 young child in great agony ; this is at first faint, then 

 grows louder, and dies away in the distance ; soon 

 another is heard, and so until day, when the birds betake 

 themselves to the water again." BISHOP STANLEY. 



The question has often been asked, " Why are birds 

 furnished with voices such as these ? " and the answer 

 has thus been given : " Beasts on the earth can discern 

 their companions by sight and smell, nor can they in a 

 few moments wander far apart from one another. But 

 birds are continually diverging from one another, and 

 even when near, many are so small that they are hidden 

 by the foliage of the trees amongst which they rest. 

 Thus a pair of Bullfinches were closely observed, as they 

 flitted along a green lane, crossing from side to side, the 

 cock slightly in advance of the hen, and it was remarked 

 that the call-note was never heard when the birds were 

 less than fifteen or twenty yards apart." 



We are told also that the song of the Lark travels 

 further than the bellowing of a bull, and that it has been 

 heard above the roar and rattle of a London street, as, 

 for once at least forsaking the well-known country 

 haunts, the bird hung poised in air above the great 

 metropolis. 



The period of incubation is the time for music ; the 

 Missel Thrush forming a remarkable exception to the 

 general rule in this respect ; and one of the great 



