THE TRAVELS OF BIRDS 



feathers drop out and fresh ones grow rapidly in 

 their places. This is called molting. 



If the feathers should fall out of one wing 

 faster than they did from the other, the bird's 

 flight would be unbalanced. It would be 

 crippled, like an aeroplane with only one plane. 

 Or if all the feathers were to fall out of both 

 wings at once, the engine would be powerless. 

 The bird could not get its food and it might fall 

 a prey to its enemies. To prevent this, the bird's 

 engines are repaired in the most wonderful way. 



The feathers begin to drop from the middle 

 of the wing; only two are lost at a time, and they 

 are from exactly the same place in each wing. 

 New ones at once sprout from the hole left by 

 the falling feather. When they are about half 

 grown, two more feathers are lost as before, one 

 from each wing. These are probably the next 

 feathers toward the outer ones. Again, the new 

 ones sprout quickly. Now the third pair is lost; 

 if the second pair fell from toward the outer- 

 most feathers, the third pair will fall from to- 

 ward the body, or the innermost ones. 



