196 ANIMAL LIFE IN THE YO SEMITE 



a rule, rather quiet. When frightened, an individual will take shelter 

 beneath or within the densest brush. 



The Sagebrush Chipmunks were still active when our party quitted 

 the Mono country on September 23, 1915. In the spring of 1916, the first 

 definite record for the speci-^s was made on May 18, although the animals 

 must have emerged from hibernation at a much earlier date. A female 

 captured on this date was already suckling young. In favorable areas 

 there is a large population of these animals. More than two dozen were 

 noted in one hour on the morning of September 17, 1915, while one of 

 our party was going from Williams Butte toward Mono Craters. On 

 several other occasions during the same week six an hour was the average 

 seen. 



Some Sagebrush Chipmunks captured near Williams Butte on Sep- 

 tember 23, 1915, had their cheek pouches crammed with seeds of Kunzia, 

 which, to the human taste, are exceedingly bitter. 



California (iRay Squirrel. Sciurus griseus griseus Ord 



Field characters. — A typical squirrel, of large size; general form slender; tail a 

 conspicuous 'brush,' about equaling body in length, broad and flat. (See pis. 33b, 34.) 

 Head and body 10 to 11% inches (256-296 mm.), tail (excluding hairs at end) 914 to 

 11 inches (240-280 mm.), hind foot about 3 inches (72-80 mm.), ear (from crown) 

 1% to IVo inches (28-36 mm.); weight 26 to 32 ounces (733-913 grams). Coloration 

 above uniform gray, with light steel gray pepper and salt effect at close range; under 

 surface of body pure white; tail gray margined with white. Voice: A hoarse, asthmatic 

 coughing note, uttered usually in slow series. Workings: Kitchen middens, consisting 

 of remains of pine cones dissected to obtain seeds; nests of large size among branches 

 of coniferous trees, or else in cavities in oaks. 



Occurrence. — Resident in Upper Sonoran and Trans-ition zones on west slope of 

 Sierra Nevada. Recorded from Pleasant Valley eastward to Aspen Valley, Yosemite 

 Valley, and Chinquapin. Inhabits large trees and ground close by. Diurnal. Solitary. 



California Gray Squirrels are present in small numbers throughout 

 the digger pine belt of the western foothills (Upper Sonoran Zone). The 

 relatively small number of trees there and the consequent limited supply 

 of nuts (upon which these animals largely subsist) is probably at the base 

 of this sparseness of the squirrel population in that belt of territory. 

 Immediately upon passing into the main forest belt of the mountains 

 (Transition Zone), characterized by the presence of the yellow pine, the 

 observer marks an increase in the numbers of these squirrels, doubtless 

 correlated with the denser stand of trees and much larger crop of various 

 nuts. At the upper margin of the Transition Zone the range of the Gray 

 Squirrel meets that of the Red Squirrel or Chickaree, a species of similar 

 food habits; and the ensuing competition seems to be one of the factors 

 operative in limiting the upward extension of the Gray Squirrel's range. 

 (See fig. 27.) 



