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 winch 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 destrov vast 
numbers of the worst pests of trees, many of which are inaccessible 
to other birds. 
This service by no means exonerates those species properlv called 
sapsuckers, nor does it free from blame woodpeckers winch 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, 190S. 
