16 Forest Birds. 



There is still another peculiarity in the anatomy 

 of the Woodpecker. When climbing a tree it must 

 necessarily keep its body very close to the trunk, or 

 the strain on the legs would be too great, and to 

 enable the bird to accomplish this, a specially-formed 

 breast-bone has been provided. 



On comparing the breast-bone of the Green Wood- 

 pecker with that of another bird of about the same 

 size, viz., the stock dove (Coluniba, senas), we 



FIG. 3. 



Breast-tone of Green Woodpecker. 

 From nature. Natural size. 



notice at once a difference in the size and shape, 

 which is truly wonderful. The breast-bone of the 

 Green Woodpecker has a very low keel (Fig. 3), and 

 this dwarfing of the keel enables the bird to cling 

 closely to the tree. The stock dove on the contrary has 

 a correspondingly high keel to the breast-bone (Fig. 4), 

 and the reason for this is soon found, for the stock 

 dove is indued with great powers of flight, and 

 since the pectoral muscles, which move the wings, are 



