CHAPTER XII 



FOOD AND FEEDING 



THERE is an intimate relation between the structure of the beak 

 and feet and the food which birds eat. 



Only a very few birds use the feet in conveying food to the 

 mouth ; but this is done by parrots, some of the smaller owls 

 and hawks, and the purple gallinule a kind of large water- 

 hen. Many birds, however, hold the food down with the feet 

 while tearing it to pieces with the beak, as in the hawks and 

 crows, for example. 



While the earliest known fossil birds were provided with teeth, 

 modern birds have the jaws ensheathed in horn ; and these 

 sheaths take very varied forms, in accordance with the nature 

 of the food. 



In birds of the finch tribe, such as the sparrow, the horn- 

 encased jaws, which form what is known as the " beak/' have 

 a conical form, and are moved by strong muscles capable of crush- 

 ing small seeds. This crushing apparatus is still further devel- 

 oped in the hawfinch, wherein three large horny " bosses " 

 having striated surfaces are to be found within the mouth. Two 

 of these are placed on the lower jaw, near the gape, while the 

 third forms a long cushion on the roof of the mouth. 

 Hard-coated seeds are held between this curious crushing 

 vice and broken with ease. In the hawks, on the other 

 hand, the beak has the upper jaw hooked, and this is used 

 as a tearing instrument whereby flesh of animals is rent in 

 pieces. 



The ducks have the inner edges of the jaws provided with 

 narrow plates or " lamellae." In the shoveller-duck these plates 

 are very long, and in their function recall the " baleen " plates 

 of whales. And the use to which these plates are put in these 

 two very different creatures is the same they act as strainers, 



