338 AXIMAL LIFE IN THE YOSEMITE 



particular food source, the California Woodpeckers show high development 

 of the storing habit. In late summer and autumn their industry in gather- 

 ing and snugly stowing away acorns according to their own peculiar 

 method is perhaps second only to that of the Gray Squirrels. The results 

 of this industry are well advertised, because of the birds' habit of ensconc- 

 ing each acorn separatelj^ in a hole in the surface of a tree trunk, bored 

 accurately to a size to fit. These acorn holes are close set over the surface 

 of the bark, sometimes from within 2 feet of the ground to a height of 

 75 feet or more. The tree or trees selected by a pair of California Wood- 

 peckers for storage purposes may not be of any species of oak at all. On 

 the floor of Yosemite Valley, ancient, partly dead incense cedars more 

 often, perhaps, than any other tree, show this woodpecker's work. When 

 the acorns have been removed the trunk of the tree is left with a curious 

 pitted appearance as if it had served repeatedly as a target for a large-bore 

 rifle. 



On November 5, 1915, along the road below the foot of Yosemite Falls 

 Trail, an old woodpeckered, dead-topped cedar trunk was studied, with 

 the following results (Grinnell, MS). The acorn pits began about 3 feet 

 above the ground and extended to a height of about 45 feet. The circum- 

 ferences of the trunk at these two limits were, respectively, 15 feet and 

 9 feet. The pits were pretty evenly distributed all around the trunk ; 

 from a series of measurements it was estimated that they averaged 5 inches 

 apart, between centers, all over the surface. This would make 2360 pits 

 on this one trunk. The pits averaged 20 millimeters in diameter by 30 in 

 depth, so they were evidently planned (and doubtless used though now 

 empty) for the fat acorns of the golden oak. This is of interest, as the 

 oaks immediately about were black oaks, which bear much smaller nuts, 

 the nearest golden oaks being about 200 yards away at the base of the 

 talus to the north. 



In one large living yellow pine near Camp Ahwahnee in Yosemite Valley 

 which had been very closely pitted, especially on the north side of the 

 trunk, it was estimated that there was an average of 30 acorn holes a 

 square foot placed all the way from 3 to 40 feet above the ground, and 

 that there was a total of 10,500 holes in this one tree ! Only the outer 

 layers of the bark were penetrated by the holes, so that no damage appeared 

 to have been done to the groAving wood of the tree. In fact, the regular 

 scaling off of bark would probably eliminate the holes altogether within 

 a few years were they not continually deepened or renewed by the birds. 



As far as observation goes, only one acorn is carried by one bird at a 

 time. We may well marvel at the ingenuity displayed in the excavation of 

 the holes, always to a diameter to admit of but a tight fit. The holes, too, 

 are just deep enough to bring the butt of the acorn flush with the bark 



