338 



PRACTICAL ZOOLOGY 



These feathers convert the narrow wings into broad surfaces 

 that enable the bird to make powerful strokes against the resist- 

 ance of the air. The body of the bird is much heavier than the 



Fie. 215. — The most important forms of birds' beaks. 



a, flamingo ; b, spoonbill; c, yellow bunting ; d, thrush ; e. falcon ; f, duck; 

 g, pelican; h, avocet ; i, black skimmer; k, pigeon; 1, shoebill ; m, stork; 

 n, arocari ; 0, stork ; p, bird of paradise ; q, swift. (From Sedgwick.) 



atmosphere and, unlike that of a land animal in walking, it must 

 be sustained as well as propelled when flying. Downward 

 strokes of the wings prevent the bird from falling just as a 



