332 ANIMAL LIFE IN THE YO SEMITE 



plumage, even to the red chin spot, at the first fall molt, and by mid- 

 September are in fine feather. Young females acquire most of the adult 

 characters at this same molt save perhaps the black breast spot. The 

 marked differences in plumage between the two sexes in this sapsucker 

 led the early naturalists, in the fifties, to designate the male and female 

 as separate species, and they were so considered until 1874; one author, 

 at least, went so far as to place them in separate genera ! 



In the Yosemite region the Williamson Sapsucker is closely associated 

 with the lodgepole pine. While this tree seems to furnish the bird's pre- 

 ferred source of forage, practically all other species of trees within its 

 local range are also utilized. We saw workings attributable to this sap- 

 sucker on the alpine hemlock, red and white firs, Jeffrey pine, and quaking 

 aspen. 



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Fig. 44. Close view of fresh work of Williamson Sapsucker on lodgepole pine. 

 Photographed at Porcupine Flat, July 1, 1915; about % natural size. 



The amount of work which this sapsucker will do upon a single tree 

 was impressed upon us while we were at Porcupine Flat in early July, 

 1915. In that locality there was a lodgepole pine {Finns tnurrayana) 

 about 60 feet high, which showed no marks of sapsucker work previous 

 to the current year. The tree was in full leafy vigor and measured 8 feet 

 3^ inches in girth at 3 feet above the ground. There were numerous 

 live branches down to within 6 feet of the ground. Twenty-six irregularly 

 horizontal rows of fresh punctures were counted on one side of the trunk, 

 the lowest being only 18^ inches above the ground, and the highest about 

 40 feet. (Part of one series is shown in fig. 44.) No one row of pits com- 

 pletely encircled the tree ; a branch had in every instance interfered with 

 the bird's completing the row at that level. But opposite the end of any 

 row, from 1 to 4 inches up or down the trunk, there was the beginning of 

 a complementary row, showing where the sapsucker after ascending to 

 clear its tail or descending to clear its head of the obstructing branch, had 

 continued puncturing in the* sidewise direction. Up and down the tree 

 the rows of punctures were from 3 to 24 inches apart. The horizontal 

 length of one series of pits 6 feet above the ground was 35 inches; of 



