PROBLEM I. The Kinds of Anhnals 



and the fall. Many of our songbirds 

 spend the summer in the more northerh' 

 states and the winter in the south. Some 

 winter over in the northern states and 

 fly to the arctic in the spring. iMigrat- 

 ing birds may perform amazing feats 

 of flying. The arctic tern, a water bird, 

 builds its nest in the far north; several 

 months later it flies to the antarctic. 

 Although the route has not yet been 

 completely traced, it is known that these 

 birds fly about ii,ooo miles each way. 

 The golden plovers travel a shorter dis- 

 tance, from Canada to South America, 

 2000 miles or more, but they fly over the 

 ocean in one stretch. They complete 

 the journey in two days and nights 

 without stopping to rest or feed. 



There are many interesting questions 

 about migration still unsolved. "How 

 can birds travel so far without food and 

 rest?" "How can thev find their way?" 

 "How can some return not only to the 

 same state and town but to the very 

 nest in which thev were reared?" And 

 difficult as any: "Why do birds migrate, 

 anyway?" 



Bird flight. Upward and forward mo- 

 tion of birds is supplied by a powerful 

 downward and backward beat of the 

 wings against the air. The large wing 

 feathers overlap while the wings beat 

 backward, but the feathers separate as 

 the wing comes forward and up. Because 

 the feathers separate during the forward 

 motion, little resistance is offered to the 

 air and not much speed is lost. When 

 birds soar, they move their wings very 

 little; instead, they depend on air cur- 

 rents, just as a glider does. 



What helps the bird in its flight? Its 

 wings are enormously long as compared 



of the Earth 



23 



Fig. 25 Compare the position of the eyes of this 

 sandhill crane with the positio?i of the o'wl''s 

 eyes. Note also the legs and bill, (new york 



ZOOLOGICAL society) 



Flycatcher \' C^" 



Fig. 26 The bill often tells you something about 

 the bird's food. For what kinds of food is each 

 bill fitted? 



