FIELD BOOK OF MAMMALS 



mountain meadows where grasses, flowering plants, and low 

 shrubs grow in the openings in the forests. It has a loud, 

 ringing call-note or whistle and when one gives the alarm, 

 others take it up, for these Squirrels live in colonies of a dozen 

 to fifty or a hundred and more. Columbianus stands stiffly 

 upright and emphasizes each call with a twitch of the short 

 bushy tail. It is a conspicuous Squirrel because of its bright- 

 colored limbs and underparts, as well as its large size. It 

 sometimes climbs up onto logs or stumps to sun itself or to 

 command a better view of the terrain. By midsummer it 

 has become very fat and goes into hibernation very early, 

 while there are yet many days of good weather. In the 

 mountains of eastern Oregon I have found this species denned 

 up by the middle of August and becoming scarce much earlier 

 than that. 



The Ground Squirrels of the sagebrush plains are typified 

 by armatiis, elga?is or oregonus among the larger species, and by 

 the mollis group for the smaller forms. These two groups may 

 occur together in a locality, but the larger members are usu- 

 ally the more abundant, noisier, and more conspicuous. 

 Armatus and its kin stand up like picket-pins, chirp a loud 

 alarm note and colonize to some extent. They become very 

 fat and hibernate early. Mollis and its subspecies are in- 

 clined to be quiet and unobtrusive in habits. The call-note is 

 characteristically a Ground Squirrel's, but is a comparatively 

 weak whistle that does not carry far. These small Squirrels 

 delay hibernating longer than their larger relatives. 



The desert-dwelling Ground Squirrels are represented by 

 the spilosoma group, the members of which are light-colored 

 and apparently well-specialized for a life in hot and dry sur- 

 roundings. They have either very short periods of hiberna- 

 tion or, where the winter is not severe, no inactive period. 

 They are abundant in sandy districts, and in the hottest 

 deserts may be practically the only mammal moving about 

 while the sun is out. The call-note is a lisping whistle. 



The Thirteen-striped Ground Squirrels live on the prairies 

 and are very easily recognized by their peculiar, much-striped, 

 color pattern. They prefer the plains districts and brushy 

 areas and do not occur in the forest or on damp ground. They 

 are abundant in many places but are often able to escape 

 observation because the long grass hides and blends with the 



214 



