WILLOW WOODPECKER 71 



would insure the health of our orchards if they were numerous enough. It 

 becomes of the highest importance, then, to study their welfare in turn. In 

 the northern and more elevated valleys of the State, it may be worth while 

 to offer them nuts or to hang out a bit of suet in winter. In the South no such 

 precautious are necessary. A fundamental consideration, however, is the pro- 

 vision of suitable nesting sites. Experiment has shown that the downy's forage 

 range dui'ing the breeding season is not extensive. The clamoring young are 

 fed by the product of nearby trees (fed, it may be, a thousand insects a day). 

 Their services, therefore, must be secured in the orchard ; and to this end the 

 orchardist must consent to leave certain dead branches — a foot or so at the 

 base of the larger ones will do — for a nesting site. Dead wood, of course, invites 

 insects ; but the most serious and frequent mistake which our California or- 

 ehardists make is to trim out all the dead wood from the fruit trees. A pair of 

 Willow Woodpeckers, or of Slender-billed Nuthatches, will clean out all the 

 dangerous pests from a dead tree, and sixteen live ones to boot. 



Grinnell and Storer (1924) made some studies of the feeding habits 

 of the willow woodpecker in the Yosemite region, of which they say : 



A pair of Willow Woodpeckers proved to be regular tenants of Curry's apple 

 orchard on the floor of the Yosemite Valley. They, or their ancestors, had 

 evidently worked there for some years, with the result that most of the 150 

 trees in the orchard showed marks of their attention, and many of the trunks 

 were fairly riddled with drillings somewhat like those of the sapsucker. * * * 



However destructive this drilling may seem to be, it does not seriously affect 

 the vitality of the trees ; the pits are but 4 to 5 mm. deep, penetrating only 

 those outer layers of the bark which after a time scale off. We should judge 

 that all evidence of this woodpecker's work is thus removed through natural 

 process within about three years. The heartwood of the tree therefore seems 

 not to be damaged at all by the woodpecker's work ; it is damaged, however, 

 by the work of the true sapsucker. Our inference from these facts is that the 

 willow woodpecker feeds on the inner layers of bark, which the bird exposes 

 through the perforations described above. We watched a bird at work ; more- 

 over, bits of inner bark-fibers were found adhering to the bristles around the 

 bill of a bird shot. 



Evidently this observation and report started the same old con- 

 troversy that arose in connection with the eastern bird, which has 

 been referred to under that subspecies. Charles W. Michael inti- 

 mated, in course of conversation with Dr. Grinnell, that they were 

 mistaken in ascribing these drillings to willow woodpeckers rather 

 than to red-breasted sapsuckers. This led to the publication, by Dr. 

 Grinnell (1928a), of the evidence produced by Mr. Michael and him- 

 self, to which the reader is referred. In spite of some evidence, and 

 more supposed evidence, to the contrary, it now seems to be generally 

 conceded that the downy woodpeckers seldom, if ever, drill these 

 holes for themselves, but that they often feed from holes drilled by 

 sapsuckers. The small amount of drilling done by the doAvny wood- 

 peckers seems to do the trees no great harm. 



Behavior. — Grinnell and Storer (1924) write: 



The quietness of the willow woodpecker, as compared with most other species 

 in its family, is noteworthy. We heard no single call note from it, and only at 



