'248 THE REASON WHF : 



" Ye birds 



That singing up to Heav'n*s gate ascend, 

 Bear on your wings, and in your notes, his praise." MILTON. 



liable to be injured, either by cattle grazing over it, or by the 

 mower. In case of alarm from these or other causes, the parent 

 birds remove their eggs by means of their long claws, to a place of 

 greater security. 



758. Why does the song of the sky-larJc, when on the wing, change 

 with its ascent and descent^ u,ruZ possess a uniform key only when 

 the bird is poised in the air ? 



Because the windpipe is the musical organ, and birds require this 

 organ less for breathing than other animals having a windpipe and 

 lungs, because of the air-cells and breathing tubes with which all 

 parts of their bodies axe furnished. 



But those different breathing organs must act with less freedom 

 when the bird is making the greatest efforts in motion, that is, 

 when ascending or descending ; and in proportion as these cease 

 to act, the trachea is the more required for the purposes of 

 breathing. 



The sky-lark thus converts the atmosphere into a musical 

 instrument of many stops, the song swelling as the bird ascends, 

 sinking with the downward flight, and with each wheel in the air 

 varying the pitch of the song. All birds that sing ascending or 

 descending have similar power, but the sky-lark has it in a degree 

 superior to any other. 



759. WTiy is the female linnet often mistaken for the male ? 



Because, when the male bird has attracted the atttention of his 

 intended captor, he instantly hops into the bush before his plumago 

 can be carefully noticed ; and, if the bush is beaten, the female bird 

 will fly out, and thus get credit for the song of her mate. 



760 The deception is further increased by the male ceasing his song and raising 

 his alarm-call as soon as he is seen, and until he disappears in the hush, for he does 

 not generally fly out ; but the female does, and wiles away the enemy from tu 



