9 6 



THE BOOK OF NATURE STUDY 



closely bound together throughout the greater part of their 

 length, and hence the foot is said to be syndactyle. In the 



climbing birds, such 

 as woodpeckers and 

 parrots, on the other 

 hand, the toes are 

 yoked together in 

 pairs, two behind 

 and two in front, 

 hence the foot is 

 said to be " zygo- 

 dactyle " or yoke- 

 toed. 



While in the 

 majority of birds 

 the beak is used 

 solely as an instru- 

 ment for the mani- 

 pulation of the 

 food, in some, as 

 in parrots, it is 

 made to play an 

 important part in 

 locomotion, as every 

 one who has ever 

 seen a parrot climb 

 knows. Similarly, 

 the feet though 

 primarily subser- 

 vient to locomo- 

 tion, may, as we 

 have seen, be used 

 for holding prey, 

 or even to convey 

 food to the mouth, 

 as in parrots. But 

 in some birds they are further modified so as to form powerful 

 weapons of offence, as, for example, in the barn-door fowl and 



F IG . 31! A, frigate bird, showing the reduced size of the legs ; 

 B, stilt, showing legs of enormous length, developed for 

 wading purposes. 



