1936] 



MAMMALS OF OREGON 



145 



black crosslines; middle of back with a large black or dusky V-shaped area 

 between posteriorly diverging light gray shoulder stripes ; lower parts and feet 

 buffy ochraceous; tail dark gray with three concealed black or dusky lines 

 along each side and around tip. Winter pelage more gray with less con- 

 spicuous markings. Young as in summer adults or more strikingly marked. 



Measurements. Average of 10 adults : Total length, 458 mm ; tail, 200 ; foot, 

 60; ear (dry), 22. Weight about the same as the California ground squirrel, 

 iy 4 :o 1% pounds (Grinnell and Dixon, 1918, p. 603). 



Distribution and habitat. These big ground squirrels extend from 

 the Columbia River south along both sides of the Cascades into 

 northern California and west of the Sacramento Valley to San Fran- 

 cisco Bay. West of the Cascades in Oregon they cover practically 

 all except the densely timbered areas toward the coast, but east of 

 the Cascades only a narrow strip along the east base of the mountains, 

 mainly in the Deschutes and Klamath Valleys, reaching their eastern 

 limit of range in Goose 

 Lake and Warner Valleys 

 (fig. 26). They are most 

 abundant in the dry inte- 

 rior Upper Sonoran val- 

 leys but are scattered well 

 over the more open parts 

 of humid Transition val- 

 leys, not usually ranging 

 high in the mountains 

 nor entering heavily tim- 

 bered areas. 



General habit s. Al- 

 though squirrellike i n 

 appearance and fairly 



o-nnrl plimhprQ thpca nr FIGURE 26. Range of Douglas's ground squirrel, 

 liniDeiS, tnes Citellus douglasU, in Oregon. 



true ground squirrels, liv- 

 ing in deep burrows of their own excavation, in hollows among the 

 rocks, or temporarily in hollow trees or logs. They often climb trees 

 for acorns, nuts, or fruit, but if surprised in treetops always rush to 

 the ground and away to the nearest burrow for refuge. Their bur- 

 rows, if deep, are usually marked by large mounds of earth at one 

 side, and by trails leading off through, the grass and weeds to other 

 burrows or to feeding grounds. They are often excavated under the 

 edges of rocks, stumps, or logs, but sometimes out in the open or even 

 in fields or meadows. 



Vigilance is the price of safety, and the utilization of open ground 

 or convenient stumps, logs, or boulders as watch towers are necessary 

 in their home economy. In a colony the sharp, barking whistle of 

 alarm may be heard at intervals, and is passed on from rock to rock 

 or stump to stump as some enemy is sighted or danger threatens. 

 It is strangely like the call note of the marmots or woodchucks, and 

 used in the same manner as warning of danger. Sometimes at close 

 quarters or on sudden alarm it runs into a long churrrrr or a guttural 

 chuck as the squirrel dives for its burrow and disappears. 



Hibernation. In late autumn these squirrels become very fat and 

 apparently hibernate for 4 or 5 months during the coldest weather, 

 which generally includes November and February. But this period 



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