THE BIRDS 



steering. Notice the movements of the tail as a bird 

 changes its course or alights and you will see how this organ 

 is used to guide the bird through the air. Feathers 

 shed water easily; and they are aided in doing so by being 

 kept more or less oily. There is an oil gland situated 

 just over the base of the tail, and birds often take some 

 of the oily secretion of this organ into the bill and distrib- 

 ute it over the plumage. Birds often preen their feathers, 

 or set them in order, by working over them with the bill 

 when they become disarranged. 



FIG. 144. Feet of birds. 



i, hawk; 2, woodpecker; 3, ostrich; 4, duck; 

 5, grebe. 



The feet of birds are covered with tough horny scales. 

 They have but four toes, one of which (and in some cases 

 two) is generally directed backward. The toes end in a 

 claw, or nail, which varies in shape according to the 

 habits of birds. Many birds which swim or wade have the 

 three front toes connected by a membrane, or web; or 

 else the sides of the toes arc furnished with flattened lobes. 

 In birds of prey, such as hawks, owls and eagles, the feet 

 are powerful and furnished with strong, curved claws 

 which adapt them for seizing prey. In many climbing 

 birds, such as the woodpeckers, there are two toes in front 



