FOES AMONG THE BIRDS 105 



the yellow-bellied sapsucker has been known to at- 

 tack 246 species of native trees and 31 kinds of in- 

 troduced trees, a total of 277 trees. Of these, 29 

 species are known sometimes to have been killed, 

 and 28 others are known to have been disfigured or 

 seriously reduced in vitality. 



But the damage done is not confined to the living 

 trees. Of greater commerical loss is the resulting 

 injury to the wood products after the tree is cut 

 down. When the tree heals and new wood grows 

 around the holes made by the sapsucker, blemishes 

 of various kinds may appear, such as staining, dis- 

 tortion of the grain, or formation of knotty growths 

 and cavities. As a result, the value of the wood is 

 reduced. These defects especially render unfit for 

 use the woods used for ornamental purposes, such 

 as mahogany and black walnut; they may blemish 

 woods valuable for some special quality, such as 

 hickory; and sometimes they may even destroy the 

 value of wood used for heavy construction purposes, 

 such as Western hemlock and Southern basswood. 

 The wood of one hundred and seventy-four species of 

 trees has been found to contain defects due to sap- 

 sucker work. It is estimated that one tenth of all 

 the trees within the sapsucker's range bears marks 

 of his work, and so wood of one tenth of the trees 

 would contain defects. This matter has been care- 

 fully investigated by the Bureau of Biological Sur- 

 vey, with the result that it is estimated that the 



