78 THE WOODPECKERS 



block ; but the bird sets his claws into the tree 

 and lifts his own body. 



Suppose the nippers had one short jaw and one 

 long one, would they then take as firm hold as 

 they do with jaws of equal length ? In perching 

 birds the hind toe is much the shortest, but 

 they sit balanced upon a limb and have merely 

 to hold themselves in position. The wood- 

 pecker climbing a tree-trunk is out of balance ; 

 he would fall ofP unless he had a firm grip ; 

 and he could not get this firm hold if his hind 

 toes were not long- enouo-h to sfive his foot a 

 nearly equal spread back and forward. Other 

 birds grasp a limb with the whole under surface 

 of their toes, but the woodpecker when on a 

 smooth, ujDright tree-trunk nips it only with his 

 toenails. Try with your own hand to hold a 

 stick as large and heavy as you can grasp, and 

 you will see that when you clasp your hand 

 around it as a perching bird takes hold of a 

 perch, it makes little difference that the thumb 

 is shorter than the fingers, but when you try to 

 nip it with your finger tips alone, you must bend 

 your fingers until they are not much longer than 

 your thumb, — that is, a pair of nippers must be 

 equal jawed. 



This simple illustration shows why the wood- 

 pecker's foot reaches as far backward as for- 



