222 



CALIFORNIA PISH AND GAME 



leaves, several "would immediately start in the general direction of the 

 sound. Tlien there would be a scramble to locate the exact spot Avhere 

 the acorn lay. In a number of observed cases there was considerable 

 competition between the deer and "digger" squirrels to see which 

 would secure the acorn. California woodpeckers were also important 

 contenders for the acorn crop, but in nearly every case observed they 

 were outwitted by either the deer or the squirrels. 



I have noted many times that during the fall and particularly 

 during the winter, mule deer are able to distinguish between good and 

 defective (blank or worm-eaten) acorns. Tn order to clieck definitely on 

 this ability, I purposely selected a number of worm-eaten and blank 

 acorns and carefully mixed them with an equal number of good acorns. 

 I scattered them about under an oak tree in the spot where mule deer 

 were accustomed to hunt for acorns, and concealed myself nearby in 

 some bushes. In some cases I was able to watch deer feeding at a dis- 

 tance of not more than ten feet. I have thus become thoroughly con- 

 vinced through such experi- 

 ments that a mule deer can and 

 does detect a defective acorn 

 without ever touching it. The 

 blank acorns are, to all appear- 

 ances, at least as far as the 

 human eye can detect, exactly 

 similar to the good acorns. 

 However, there is one difference, 

 and that is that the blank acorns 

 are very light in weight. This 

 difference can easily be detected 

 by a person taking them into his 

 hand. However, I have been 

 unable to find any character 

 whereby they can be distin- 

 guished b}^ the human eye at a 

 distance of even one foot. The 

 worm-eaten acorns usually show 

 very small holes, wliieh might 

 possibly give the deer some clue. 

 However, my observations have 

 shown conchisively that the deer 

 were able to distinguish such 



they were 

 Since the 

 acorns in question were not even touched by the deer, the sense of 

 feeling could not have played any part in the selection. Therefore, I 

 concluded that the sense of smell was the medium through which such 

 acorns were detected and left untouched by the deer. In one instance 

 I tested this power of discrimination of a large mule deer buck, and 

 found that he was able to select the good acorns unerringly and that 

 the worm-eaten and particularly the blank acorns were left untouched. 



Fig. 75. This buck fed for five minutes 

 on the pungent leaves of the California 

 laurel tree and I'eturned to brow.se on the 

 same sapling: three times in fifteen 

 minutes. Yosemite, June 26, 1927. Mus. 

 Vert. Zool. No. 5392. 



wormy acorns when 

 hidden beneath leaves and thus completely out of sight. 



