CHAPTER XI 



DIFFERENT MODES OF FLIGHT 



It has never been quite determined how a bird 

 flies. FUght differs according to the species, 

 and is characteristic in so far that we can 

 generally tell what manner of bird it is from 

 the style of flight. Some birds fly in a straight 

 line, some with an undulating flight, and others 

 erratically. Then there are the slow and 

 rapid fliers ; but when all is said, the wing 

 action is the same, viz., a straight up-and- 

 down movement, more or less rapid. 



It may be said that a straight up-and-down 

 flapping action, though it may have the effect 

 of lifting a bird into the air, would not propel 

 it in a forward direction on a level plane. 

 Some beUeve that the forward motion is 

 obtained by a " scooping " action ; it is said 

 that the wing moves in the form of a figure 8, 

 something on the principle of an oar when 

 pulled or pushed through the water and 

 " feathered " back into position for the next 

 stroke, a mode of propulsion which serves well 



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