106 STRUCTURE AND COMPARISON. 



fully explained if we knew what food the bird preferred when 

 at home. 



We have had bills that turned up and down, but no one 

 would admit that a bill that turned 

 sideways could be possible except 

 by accident. Yet* here is that " ac- 

 cident." Every egg laid by this 

 little plover produces a bird with 

 FIG. 34. BILL OF CROOK- the bill crooked to the right. It 

 BI LLED PLOVER. is a New Zealand bird, but unlike 



the spoon-billed sandpiper, it has 

 never strayed to our shores. 



What is a bird with such a bill to do ? How can any bird 

 be better fitted for his work by having a bill bent to one side 

 so that he cannot feed unless his food is on the right side of 

 him? But this bird gets his food by trotting along rocky 

 river-beds and picking up small forms of animal life that creep 

 in under the loose stones of the dry channels for greater security 

 and moisture. Therefore, since his course lies never in a 

 straight line and usually in a circular direction, it is no disad- 

 vantage to him to travel always in one direction, or perhaps 

 it is a decided advantage not to have to turn in his tracks so as 

 to face the stone at every stop he makes. 



A very curious point about this bird's coloration is worthy 

 of notice. His constant habit of turning to the right leaves 

 the left side open to danger ; all his foes must approach him 

 on that side. He has across his breast for ornament a black 

 band; and it has been noticed that while this is three-fourths 

 of an inch wide on the right side, it is not more than half an 

 inch Vide and is much lighter in shade on the exposed left 

 side, thus varying both in width and color. Think of it, all 

 the other birds in the world are bisymmetrical j that is, alike 



