COMPENSATION FOR INJURIES. 9 



nearly all of them at times choose living trees. Some use living 

 trees almost exclusively and dig a new hole each year; others occupy 

 the same nest year after year. The Williamson sapsucker is one of 

 the species which habitually nest in living trees. Joseph Grinnell 

 relates that in the San Bernardino Mountains tamarack or lodge- 

 pole pines (Pinus murrayana) are selected by that species as nest 

 trees, usually old ones with the core dead and rotten but with a live 

 shell. In one tree he noted a series of 47 holes which penetrated the 

 trunk on all sides up to about 35 feet. Besides these there were 

 many smaller drillings. When once selected by these sapsuckers a 

 tree is doomed, but probably not more than 1 tree in 500 is appro- 

 priated by the birds. 1 



ATTACKS OF TREE ENEMIES AIDED BY WOODPECKERS. 



Unlike the surgeons of the human body, woodpeckers neither .close 

 the wounds they make nor apply antiseptic treatment, but leave 

 the cuts open to infection. Hence an opportunity is given for a host 

 of enemies, such as bacteria, fungi, and insects, to enter the wound 

 and further injure the tree. While the birds are at fault in so far as 

 they create conditions allowing the inception of damage by these 

 formidable tree enemies, it is evident that blame for all the ensuing 

 injury can not be placed upon them, and it must be admitted that 

 insects, fungi, and bacteria do immense damage with which wood- 

 peckers are in no way connected. It should not be overlooked, 

 however, that old woodpecker holes are of use also to many friends 

 of trees, as they furnish nesting sites for bluebirds, titmice, chickadees, 

 and other insectivorous birds. 



COMPENSATION FOR INJURIES DUE TO FOOD AND NEST EXCA- 

 VATIONS. 



After all, however, the question to be decided in regard to the 

 injuries incident to insect hunting and nest excavating by wood- 

 peckers is : Do the services the birds render in destroying the enemies 

 of trees outweigh the damage they inflict? In Bulletin 37 of the 

 Biological Survey it is shown that most woodpeckers destroy vast 

 numbers of the worst pests of trees, many of winch are inaccessible 

 to other birds. 



This service by no means exonerates those species properly called 

 sapsuckers, nor does it free from blame woodpeckers which attack 

 structures valuable to man. It does mean, however, that in general 

 we can safely ignore the minor injuries committed by woodpeckers 

 in pursuance of their natural mode of life, and that in practically all 

 cases (with the exceptions noted) woodpeckers living in forests, 

 groves, or orchards do a great deal more good than harm. 



i Grinnell, Joseph, Univ. Calif. Pub. Zool., V, 64-65, 1908. 



