WOOBFECKEllS 



333 



another close by, 44 inches. Individnal punctnres in a row were O.-l to 

 0.6 inches (10 to 15 mm.) apart. Three typical fresh punctures all meas- 

 ured 0.16 inches (4 mm.) high, with respective widths of 0.2, 0.37, and 

 0.4 inches (5, 9, and 10 mm.). The nearly constant vertical dimension, 

 just as in the case of the drillings of the Red-breasted Sapsucker, was 

 probably due to the size of the bird's bill, while the varying horizontal 

 dimension resulted from varying amounts of work done in the individual 

 pits. Many of the holes were bleeding and probably would have been 

 visited again and again by the sapsucker. Earlier drillings of the current 

 season had stalactite-like streamers of hardened pitch below them, some 

 being 2 feet in length. 



In addition to the exudation of sap, these series of puncturings cause 

 responsive growth action on the part of the tree. Rings or swellings in 

 the wood and bark develop at the sites of the punctures. A tree drilled 

 to the extent of the one described above would in a few years show a series 

 of swollen rings, one at each 

 line of punctures (fig. 45). And 

 the site of each individual punc- 

 ture develops into a small knot- 

 like growth. A dead lodgepole 

 pine at Aspen Valley showed 

 clearly that it had been drilled 

 extensively in earlier years ; for 

 the dead and partly barkless 

 bole was little more than a suc- 

 cession of swollen rings. Many 

 trees exhibiting intermediate 

 stages in this scar-like affliction 

 were observed. 



During the winter months 

 when sap is practically at a 

 standstill in the coniferous trees 

 at high altitudes, the William- 

 son Sapsucker must needs seek 

 other fare. A few of our own 

 observations added to those of 

 other naturalists suggest that 



during the winter season the birds may forage in large part on dormant 

 insects or on insect larvae hidden in crevices in the bark. If such is the 

 case, whatever the damage done hy these birds to the forest as a whole 

 during the summer months, it is partially offset by their winter-time 

 activity. In any event, the attacks of the Williamson Sapsucker on the 



Fig. 45. Eesult of work of Williamson Sap- 

 sucker on bark and trunk of old lodgepole pine. 

 Photographed at Porcupine Flat, July 1, 1915. 

 See discussion in text. 



