192 THE STORY OF THE BIRDS 



long pointed wings, the weak feet, and the 

 wide gape of the Swallow all indicate an insect 

 diet secured whilst the bird is coursing about 

 the air. The equally long wings, in combi- 

 nation with the powerful feet with their sharp 

 claws, and the strong hooked and toothed bill 

 of the Falcon, tell us as plainly as spoken 

 words could do that this bird is a hunter of 

 living creatures — that it preys upon flesh. The 

 chisel-shaped bill of the Woodpecker, with the 

 curiously modified tongue, the zygodactyle feet, 

 and the stiff -pointed tail, betray the bird's 

 partiality for insect food and the peculiar 

 methods of obtaining it. 



The modification of the bill in some groups 

 is very much more extensive than in others. 

 A diverse amount of modification in the bill 

 seems correlated with a high degree of organi- 

 sation, and its consequent variety of habit 

 and food. Thus we should expect to find, 

 and really do find, the greatest amount of 

 variation in the bill amongst the most highly- 

 organised group of birds, the Passeriformes. 

 Here we cannot say that any shape of bill is 

 typical, no more than we can assert that any 

 one kind of food is common to the group of 

 the insectivorous Passeres — such as Warblers, 



