FOOD AND FEEDING 93 



The nightjars, swifts, and swallows have extremely short 

 beaks and enormously wide mouths. These birds feed upon 

 insects, which they pursue during free flight. Here a large 

 beak is not wanted ; the prey is snapped up and passed into the 

 mouth at once. To facilitate this method of feeding, the mouth 

 of the nightjar is fringed with very strong bristles. In Fig. 28 

 these various forms of beak may be more carefully studied. 



Reference has already been made to the use of the tongue 

 in feeding ; we return to the matter here to refer to the wonder- 

 ful tongue of the woodpeckers. This is cylindrical in shape, 

 and of great length. Worked by powerful muscles attached to 



?.B.MT 



FIG. 29. Dissection of the head of a woodpecker, to show the great length 

 of the tongue, the bony supports or " roots " of which are so long that 

 they have to be carried round the back of the head, and over the crown, 

 finally passing to rest in a chamber formed in the beak. 



long and slender supports known as the tongue- or hyoid-bones, 

 this organ can be thrust far out of the mouth when feeding. 

 At this time it is covered with a very sticky juice having the 

 tenacity of bird-lime, which is formed by a large pair of glands 

 placed on each side of the lower jaw. Thus coated it forms 

 a most effective weapon when thrust into a crowd of ants 

 upon which the woodpeckers largely feed or darted out upon 

 such other insects as may be deemed delectable morsels ; for 

 there is no escape for the victim touched by this extremely active 

 and worm-like death-trap ; and the struggling bodies are swiftly 

 borne back to destruction. 



Some birds contrive to hold food in the mouth immediately 



