INTRODUCTION. 11 



If the 16 species of woodpeckers herein discussed were arranged 

 in the order of their usefulness according to their food, they would 

 stand about as at top of page 10, except that the 3 species of Sphy- 

 rapicus, owing to their sap-sucking propensities, might be placed 

 at the foot of the column. It is unfortunate that so few stomachs 

 of the three or four species nearest the top have been received, but 

 probably those examined were in no way exceptional. The 2 

 species of Picoides are among the most useful birds, especially in the 

 forest, of which they are preeminently the conservators. More than 

 60 per cent of the animal food of these two birds consists of the larvae 

 of wood-boring beetles, which they dig from the bark and wood of 

 trees. The two species Dryobates pubescens and D. villosus do not 

 fall far behind in this good work, and several others eat very appre- 

 ciable quantities of wood borers. Among the beetles eaten by the 

 different birds are naturally some useful species, such as the preda- 

 ceous ground beetles (Carabidge) or tiger beetles (Cicindelida3) . The 

 redhead eats useful beetles to the extent of 7.34 per cent of its diet, 

 the Lewis woodpecker, with 6.7 per cent, stands next on the list of 

 offenders in this respect, followed by the red-shafted nicker with 

 3.9 per cent, and the eastern nicker with less than 2 per cent. No 

 other species had eaten so much as 1 per cent of these beetles. What- 

 ever sins woodpeckers may commit, the destruction of useful beetles 

 is not one of them. 



Nearly all the vegetable food, except a few seeds, including some 

 grain, can be included under three items fruit, cambium, and mast. 

 The greatest interest attaches to the cambium, which is a jelly like 

 substance found just under the bark of growing trees and from which 

 both wood and bark are formed. The smaller species of wood- 

 peckers have been accused of pecking the bark from fruit and forest 

 trees to an injurious extent in order to get this substance. While 

 nearly all members of the family eat some cambium, the only ones 

 that really do much harm by the habit appear to be the yellow- 

 bellied sapsucker (Sphyrapicus varius) and others of the same genus. 

 With the yellow-bellied sapsucker cambium amounts to about 17 per 

 cent of the annual food and in April reaches 48 per cent. As the 

 substance is often semifluid, probably much passes almost immedi- 

 ately out of the stomach, leaving only the harder and less easily 

 digested part, so that a much larger amount is eaten than is shown 

 by stomach examination. 



In obtaining the cambium the bird sometimes denudes the tree of 

 its bark over a considerable area, and so ruins it for any economic 

 use except fuel; at other times a series of single punctures are made 

 in lines extending around the tree, and as new layers of wood grow 

 over these, the indentation at each puncture becomes less and less 

 pronounced. If, after some years, this timber be cut and sawed, 



