684 THE MONTHLY BULLETIN. 



burrow some fifty feet distant from where the rattlesnakes had been. 

 There was no way of determining whether the presence of the snakes 

 had influenced this action, but it was evident that this squirrel made 

 no effort to fill up the entrance to the burrow which had been pre- 

 empted by the snakes. It is a popular notion that ground squirrels, 

 when the opportunity offers, bury snakes alive. 



As for mammals as enemies of ground squirrels, the evidence most 

 readily obtainable is derived from examination of the excrement of 

 the former. Coyotes have regular places for deposit of excrement, on 

 hill tops or ridges. Bones and teeth of ground squirrels frequently 

 have been found represented in these deposits (J. Grinnell, MS). The 

 remains of two freshly eaten ground squirrels were found in the stomach 

 of a wildcat killed in central San Diego County (J. Dixon, MS). 



As to food, the California Ground Squirrel shows a wide range of 

 taste, even though there are at the same time decided preferences. He 

 cheerfully adopts substitutes when favorite foods are lacking; he is 

 not averse to taking considerable barley with his wheat. A list of all 

 the plants eaten by the ground squirrel would be a very long one, and 

 if locality be taken into account great variation would doubtless be 

 found from place to place. The above general statements will be borne 

 out, in part at least, by the data presented in the paragraphs to follow. 



On the University campus at Berkeley, on March 13, 1918, the ma- 

 jority of the California Ground Squirrels were feeding on the tender 

 leaves of alfilaria {Erodium). A female squirrel was observed by the 

 junior author at this time to eat the leaves of young plants of the star 

 thistle (Centaurea). On San Emigdio Creek, Kern County, on April 

 28, 1918, a squirrel was seen to disappear down a hole carrying a sheaf 

 of freshly cut heads of foxtail (Hordeum) held tightly in his mouth. 

 A few minutes later this squirrel was gassed and when the burrow was 

 dug out the fresh foxtail heads were found on the edge of the nest. 

 Previously this squirrel was seen to gather heads of both foxtail and 

 alfilaria, but preference was given to the latter (J. Dixon, M,S). The 

 young as well as the old squirrels seem to prefer alfilaria when obtain- 

 able to any other plant. 



In the region about Walnut Creek, Contra Costa County, on July 26 

 and August 16, 1918, the authors found ground squirrels feeding exten- 

 sively on seeds of bur clover (Medicago hispida). Dried burs of this 

 plant were abundant on the hillsides in the near vicinity of the squirrel 

 burrows, and although there was a plentiful supply of barley on the 

 adjacent stubble fields this was in major part passed up in favor of 

 the clover seeds. Hulled seeds of the bur clover were found to pre- 

 dominate in the cheek pouches and the stomachs of the score or more 

 squirrels that were shot. This fondness on the part of the ground 

 squirrels for bur-clover seed suggests a possibly better way of poisoning 

 these rodents by using the entire bur of the clover than by the use of 

 barley, wheat or other grains, which are now so badly needed for human 

 consumption. 



In southern California the seeds of the plant known as wild cucumber, 

 manroot, or chilicothe {Echinocystis macrocarpa) is eagerly sought by 

 ground squirrels. Gnawed hulls of the seeds of this plant are fre- 

 quently found in large quantities near the summits of rock piles where 

 the husking or lookout stations of the squirrels are located. In Yosemite 



32 



