FORM AN"D HABIT; THE FEET. 



29 



Sparrows nse both feet in searching for food, jumping 

 (piickly baclvward and throwing the leaves heliind them. 



Parrots use tlieir foot as a hand. Some Ilawka cany 

 nesting material in it, and all birds of 

 prej strike tlieir quarry with their 

 strongly curved claws, which are then 

 used to carry, or hold it while it is 

 being torn by the bill. The foot of 

 the Fish Hawk is a magnificent oro-an. 

 The nails are strong and well curved ; 

 the inner surface of the toes is set with 

 sharp, horny spikes, and the outer toe 

 is partly reversil>le, so that the Ijird 

 grasps its slippery prey from four dif- 

 ferent points. 



As a weapon the foot is especially 

 effective, the use of spurs being too 

 well known to require comment. Os- 

 triches kick with their feet, and can, it is said, deliver a 

 blow powerful enough to fell a man. 



But by far the best instance of modification in the 

 structure of the feet is furnished Ijy Grouse. It is an 



Fig. 15.— Foot of Fish 

 Hawk, showing large 

 claws, and spicules on 

 undei' surface of toes. 

 (Vs natural size. ) 



Fia. 10.— Nalied toes of KufFcd Grouse in sununer ; fringed toes of Paiffed 

 Grouse in winter, ("/a natural siz.e.) 



unusual case of seasonal adaptation in form. During the 

 summer the toes of Grouse are bare and slender, but as 



