Tails 



409 



We notice that birds which have very short tails are 

 unable to turn quickly and that their flight is very direct, 

 or even where there is a long tail, if it is principally for 

 ornament and not well muscled, it is of little use in help- 

 ing its owner to change the direction of flight. The 

 partridge-like tinamous of South America are good exam- 

 ples of the first-mentioned group. Their tails are small 

 and useless, and when once the bird launches itself into 



Fig. 324.— Tail of Pelican alighting. 



Fig. 325.— Tail of Tern in flight. 



the air, it can keep on only in a straight line and is at 

 the mercy of every cross-current of air. A more familiar 

 case, which any one may observe, is a Song Sparrow, or 

 other small bird, which, from accident or from some irregu- 

 larity of moult, has lost all or most of its tail-feathers. 

 Instead of rismg with the strong, darting flight ^^•ith 

 which such a bird is accustomed to make its escape from 

 our path, its flight under such conditions is weak and 

 direct, like the trial efforts of a young bird. 



