GROUND HQVIBRELS 163 



from other states, because of its different appearance from that of prairie 

 dogs and other squirrel-like animals of the more eastern parts of North 

 America. It is to be seen in numbers from the windows of trains passing 

 through the San Joaquin Valley, and is occasionally observed along the 

 railroad in the Merced Caiion ; while along all of the auto roads from the 

 west leading into the Yosemite National Park it compels attention at almost 

 every turn. Here individuals are prone to dash across the road almost 

 under the wheels, uttering their startled cries and stirring up small clouds 

 of dust to mark their precipitate rout. To the residents of the Sierran 

 foothills this species is known as 'digger squirrel' in recognition of its 

 propensity for burrowing and to distinguish it from the 'tree' squirrels. 

 Gray and Eed, which inhabit the middle and higher altitudes in the 

 mountains. 



Sdurusd.albolimbatus Citellus beldingi /\ Cr''S^'"o\. , . > 

 Callospermophilusc.chrysodelrus i ■ -^/\ \! p':hrv.56deii-u j ^S.albolimbdtu s 



Fig. 27. Cross-section of the Sierra Nevada through the Yosemite region showing 

 general zonal and altitudinal distribution of Squirrels and Marmot. 



The California Ground Squirrel is distinguished from the Gray and 

 Red squirrels by the presence of whitish shoulder patches, by a less bushy 

 tail, and by ground-dwelling habits; from the Belding Ground Squirrel 

 by larger size, and by much longer and broader tail, which undulates as 

 the animal runs along the ground; from the Golden-mantled Ground 

 Squirrel and the species of chipmunks, by larger size and by the absence 

 of stripes of co/itrasted bright color along the sides of the body. 



The California Ground Squirrel is most abundant on the plains of the 

 San Joaquin Valley and in the adjacent foothills, in the Lower and Upper 

 Sonoran zones ; it is less numerous in the Transition Zone and but sparingly 

 represented in the Canadian. The highest altitude at which we observed 

 it was 8200 feet, a few miles east of Merced Lake. The California Ground 

 Squirrel shares the Canadian Zone with the Golden-mantled Ground 

 Squirrel, which fact may account in some degree for the lessened numbers 

 of the former in that high zone. (See fig. 27.) Above, in the Hudsonian 

 Zone, the meadowlands are inhabited exclusively by the Belding Ground 

 Squirrel, while about rock slides and on the hillsides only the Golden- 

 mantled is to be found. On the east slope of the mountains the California 



