618 The Animal Kingdom 



table insect trap formed of a short beak and a wide mouth surrounded 

 by long sensitive hairs. Woodpeckers have long stout bills for prob- 

 ing in wood. The woodcock has a long bill, the tip of which is sensi- 

 tive and can be opened without opening the rest of the bill. This is 

 useful for probing in soil for grubs. Birds of prey such as the hawks 

 have heavy, flesh-tearing beaks. A further remarkable adaptation is 

 found in the sieving bills of the ducks. Water and mud are taken in 

 through the tip of the beak and food is strained out by the sievelike pro- 

 jections along the sides. Many fish-catching birds such as the bittern 



Fig. 205. — Structural variations in the bills of birds. A, Generalized beak of 

 ring-necked pheasant; B, straining beak of canvasback duck; C, spearing beak of 

 bittern; D, probing beak of greater yellowlegs; E, beak of brown pelican; F, chisel- 

 like beak of hairy woodpecker; G, carnivorous beak of Swainson hawk; H, insectiv- 

 orous beak of nighthawk; I, insectivorous beak of myrtle warbler; J, graminivorous 

 beak of black-headed grosbeak; K, beak of red crossbill. (By permission from 

 Animal Biology by Wolcott, copyright, 1946, by McGraw-Hill Book Company, Inc.) 



