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 with 

 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. 



