CALIFORITIA WOODPECKER 217 



around acorn holes had been gnawed by rodents, as unmistakably 

 proved by the tooth marks. The acorns were gone from some of these 

 holes, but not from all, thus showing that the marauders had failed 

 in some of their efforts." 



Summarizing his first paper, he makes the following statements: 



As to hole drilling : While the holes are made expressly for the reception of 

 acorns, many holes are probably made which are never used, holes are made at 

 seasons of the year when there are no acorns to store, and large numbers of 

 perfectly serviceable holes seem to be abandoned even in localities where both 

 birds and acorns are abundant, and new holes are being made. 



As to the storing business itself: While this is of distinct service to the food 

 necessities of the woodpeckers, the instinct sometimes goes wrong to the extent 

 of storing pebbles instead of acorns, thus defeating entirely the purpose of the 

 instinct. Again, large numbers of acorns are sometimes stored, the use of 

 which is so long delayed that the acorns become wholly or largely unfit for 

 food, and this in places where the bird population seems normal. Finally, acorns 

 are sometimes stored in such fashion as to make them easy prey for marauding 

 rodents, when with some definite foresight and a little more work such exposure 

 could easily be largely avoided. 



In his second paper (1922), after further observations, he states^: 



My previous surmise that the birds are more interested in the grubs con- 

 tained in the acorns than in the acorn meats has not been substantiated. What I 

 could make out while in camp among them, by watching them gather and eat 

 their breakfasts, was to the effect that good uninhabited acorns were chiefly 

 used. Again and again birds were seen to pick nuts from the top-most branches 

 of the black oak, fly with them in their beaks to some approximately horizontal 

 surface of a large limb on a pine or another oak, make the surface aid them 

 somehow (I never could see exactly how, as the "brealffast tables" were, of 

 course, all on the upper surfaces of the limbs, and too high for my vision) in 

 breaking and tearing open the nuts. Apparently cracks and chinks in the table 

 top serve as holders for the acorns while they are being opened and eaten. 

 This is indicated by the fact that dead and partly decayed trees or parts of 

 trees were mostly used. I saw no indication of the feet being used in handling 

 the nuts. The litter on the ground under the dining trees, consisting of shell 

 fragments and lost bits of meat, indicated grubless nuts almost entirely. This 

 result as to the use of mast is in agreement with Beal's examination of the 

 stomach contents of our woodpecker. 



Charles W. Michael (1926), in the Yosemite Valley, made the inter- 

 esting discovery that the California woodpecker has been known to 

 learn by experience and to show some intelligence in its acorn storing. 

 For a number of years when acorns were abundant no extensive stor- 

 ing was done, yet the woodpeckers liA'ed in the valley all winter. 

 Then came a lean year, with no acorn crop, when no storing could be 

 done ; and that winter the woodpeckers were forced to leave the valley 

 for lack of food. The following year there was a bountiful crop of 

 acorns, and the woodpeckers, having learned by experience, were 

 busy filling up their storehouses. "From the above observations," he 



^ Prof. Ritter's extensive book (193S) on the California woodpecker appeared while this 

 bulletin was in press. — Editor. 

 90801—39 15 



