40 THE STORY OF BIRD-LIFE. 



be the case if all required the same kind of food. 

 One eats what another leaves. A verification of 

 the old adage " what is one man's meat is another 

 man's poison." The outcome of this effort at 

 adaptation to different localities, the strus^gle to 

 hold unoccupied corners, is seen in the different 

 modification of organs and forms of the body in 

 the various animals and plants around us. In 

 the case of birds we have numerous examples. 

 AYe have birds that have become specially modi- 

 fied, so that they are enabled to seek their food 

 beneath the surface of the waters, birds that 

 obtain their food in mid-air, birds that delve 

 beneath the ground, birds that tax our fields and 

 orchards, birds that eat other birds, and a dozen 

 intermediate stages of feeding and procuring 

 food : some of which we shall discuss pre-ently. 



When we want to find out how an unknown 

 animal feeds we look first of all at its mouth. 

 The entrance to a bird's mouth is its beak. This 

 is a part of the head which is produced forwards, 

 more or less into a point. This point is divisible 

 into two parts or jaws, an upper and a lower, 

 both of which are encased in a horny sheath of 

 more or less density. On the form and texture 

 of this sheath much depends. Moreover, we 

 shall soon see that it is not the beak that makes 

 the bird, for we have beaks of similar form 

 belonging to birds not at all related — the like- 

 ness has been brought about by the similar 

 mode of feeding. At one time the shape of 

 the beak was considered a very important 

 character by which to judge of a bird's relation- 

 ship. It was treated somewhat after the fashion 



