152 



NORTH AMERICAN FAUNA 



[No. 55 



General characters. Size between Citellus mollis canus and C. oregonus; 

 ears and tail short ; soles mainly naked ; fur short and thin. Colors about the 

 same at all seasons and ages, upper parts ashy gray, the whole back thickly 

 dotted with small white spots; nose and hams and lower surface of tail pale 

 rusty ; lower parts and feet buffy. 



Measurements. Average of 10 adults : Total length, 222 mm ; tail, 44 ; foot, 

 34.5; ear (dry), 8, from crown, 2. 



Distribution and habitat. These little fat, short-tailed, gray, 

 speckled-backed ground squirrels are abundant in the hot, dry, sandy, 

 Upper Sonoran Zone bottom of the valley south and east of the 

 Columbia Eiver from near the mouth of the John Day Elver to Walla 

 Walla, and north over the lower parts of the plains of the Columbia 

 to Spokane, Wash., and east in the Snake River Valley to Lewiston, 

 Idaho (fig. 29). They meet but rarely overlap the ranges of the 



larger Oregon and Co- 

 lumbian ground squir- 

 rels, which may help to 

 determine their bound- 

 aries, but apparently the 

 limits of range of all are 

 zonal. They occupy the 

 open sagebrush or grass- 

 land country and show a 

 preference for sandy soil 

 where digging is easy. 



General habits. Pro- 

 tected by their gray and 

 speckled colors in the 

 gray vegetation of their 

 somewhat arid habitat 

 these little squirrels 

 would be inconspicuous 

 but for their great numbers and their lisping whistle, which sounds 

 from one and another on all sides over the grassy prairies, from the 

 steep hillsides, the gulch banks, and sandy bottoms. They are social 

 in habits, but not colonial, gathering most abundantly where there 

 is most food, living in harmony and to some extent mutually bene- 

 fited by numbers, always on the watch for danger and ready to signal 

 an alarm. When undisturbed they creep quietly about or run low 

 over the ground. At the first suspicion of danger, they stand 

 straight up on the hind feet, the short tail not reaching the ground, 

 and the hands dropped at the sides^ as they watch for the menace. 

 A whistle from one will bring all within hearing to their picket-pin 

 attitude of vigilance, and as the whistle is passed along others take 

 it up until hundreds may be seen standing motionless. In places the 

 ground is honeycombed with their burrows (as many as 620 have 

 been counted on a measured acre), and in case of danger each squirrel 

 darts down the nearest burrow. A whole field of them may dis- 

 appear in a twinkling. 



The burrows are generally simple, or but little branched, going 

 down 4 or 5 feet and back several feet to a nest cavity. There seems 

 usually to be but one opening to the surface, but this may apply only 

 to the new or temporary burrows. No breeding or wintering dens 

 were explored. 



FIGURE 29. Range of the sage and Townsend's 

 ground squirrels in Oregon : 1, Citellus mollis 

 mollis; 2, C. m. canus; 3, C. m. vigilis; 4, (7. 

 townsendii. Type localities circled. 



