HABITS OP SAPSUCKEES. 



17 



Spiny tongue of downy woodpecker (Dryobates pubescens). (From 

 Lucas, Rept. U. S. Nat. Mus., 1895.) 



In keeping with their peculiarities of structure, these brush- 

 tongued woodpeckers have peculiar food habits. They are the true 

 sapsucking and cambium-eating species. They girdle and kill many 

 trees, either by destroying extensive areas of the cambium or more 

 commonly by removing many small pieces in such a way as to sever 

 most if not all the channels carrying the elaborated sap from which 

 both wood and bark are formed. 



The three species are probably equally to blame. While it has 

 been asserted that the red-breasted and Williamson sapsuckers harm 

 trees less than the yellow-bellied, these statements are probably 

 founded on in- 

 sufficient infor- 

 mation. There 

 is a dearth of 

 data respecting 

 the habits of 



these two woodpeckers, but similarity of structure and the evidence 

 of stomach examinations indicate that the three species of sapsuckers 

 are much alike in their cambium-eating habits and hence all three are 

 injurious to trees. The Williamson sapsucker, however, is strictly an 

 inhabitant of pine forests and aspen groves at considerable elevations, 

 and therefore under present conditions is not likely to injure trees of 

 great value to man. 



Stomach examinations show that the red-breasted sapsucker con- 

 sumes enough cambium and bast to average 12.16 per cerit of its 

 food. The same food constitutes 12.55 per cent of the stomach con- 

 tents of the Williamson sap- 

 suckers examined and 16.71 

 per cent of the yellow-bellied 

 woodpecker's diet, an aver- 

 age amount for the three of 

 13.8 per cent. It must be 

 noted also that cambium is a very delicate, perishable material, at 

 certain times no more than a jelly, and thus never receives a percent- 

 age valuation in examinations of long-preserved stomachs correspond- 

 ing to its bulk when first swallowed. Neither do we get any record 

 of the sap consumed by these birds, and they are inordinate tipplers. 1 

 Hence the value of the percentages cited lies not so much in their 

 accuracy as to the quantity of cambium eaten as in the fact that they 

 indicate a steady consumption of this important substance. There 



Fig. 4.— Brushy tongue of sapsucker (Sphyrapicus varius). 

 (From Lucas, Rept. U. S. Nat. Mus., 1895. 



1 A yellow-bellied sapsucker has been observed to remain within a yard of some of its holes in a maple 

 tree, drinking the sap at frequent intervals, from 10 a. m. to 5 p. m. 



99068°— Bull. 39—11 2 



