8 WOODPECKEBS IN RELATION TO TREES. 
injuries are offset by beneficial activities of the birds will be discussed 
later. 
HOLES MADE IN DIGGING OUT INSECTS. 
As a rule the holes made by woodpeckers when digging out insects 
are not Large, and there is every reason to believe that most of them 
heal quickly without noticeably disfiguring the exterior of the trees. 
They cause distortion and staining of the wood, however, as do all 
injuries to the cambium. These defects often resemble those which 
result from sapsucker work, but they generally occur in otherwise 
unsound trees and are much less numerous and important. However, 
wounds made by woodpeckers when digging out borers deeply buried 
in the wood, by reason of their larger size, often result in bleaching 
the wood (see PI. Ill, fig. 6), a feature rarely observed in connection 
with the smaller sapsucker pecks. 
Our two largest species of woodpeckers, the pileated and the 
ivory-billed, dig great pits or furrows in living trees or split off large 
chips. Plate III, figures 1 to 5, illustrates large wounds made by 
pileated woodpeckers. F. M. Chapman says: "I have seen an open- 
ing made by a pileated woodpecker in a white-pine tree 12 inches 
long, 4 inches wide, and 8 inches deep, through perfectly sound 
wood to reach the larva? at work in the heart of the tree." 1 These 
large woodpeckers occasionally riddle trees which show no signs of 
insect attack, but this is so unusual as not to warrant hostility 
toward these fine birds, which are disappearing only too rapidly as 
man encroaches upon their domain. 
All woodpeckers chip off considerable wood from dead trees and 
branches to secure the insects therein. In spite of the good done 
by destroying these insects, in some countries woodpeckers are held 
in disrepute because they reduce the quantity of firewood, a view 
not likely to be adopted in the United States. 
Indeed, the offices of woodpeckers in capturing the various wood- 
boring insects may be likened to those of the surgeon who removes 
diseased parts from the human body. Not only do Ave deem the 
surgeon's achievement praiseworthy, but we pay him well for doing 
it. We should maintain the same attitude toward the woodpeckers, 
surgeons to our trees. Practically all the compensation they demand 
is the privilege of excavating nests and sleeping shelters in trees. 
EXCAVATION OF NEST AND SHELTER CAVITIES. 
There are 24 species (and several subspecies) of woodpeckers in 
the United States, and although most of them usually select dead 
Btubs (>!• limbs or partly decayed trees in which to make their nests, 
' Chapman, F. M.. Color Key to \". \. Birds, p. IK L903. 
