180 ANIMAL LIFE IN THE YO SEMITE 



the ground from a height of ten or fifteen feet in the tree. The animal 

 seemed unhurt and quickly made off and climbed a white fir in the vicinity. 

 A jump to earth of considerable magnitude seemed to have been under- 

 taken voluntarily, as an extreme measure of safety, perhaps, and accom- 

 plished without injury. 



It is not uncommon to see two chipmunks engaged in a play-like pur- 

 suit of one another which may last for minutes at a time and carry the 

 two over and beneath logs, through brush, across open places in the 

 forest, and not infrequently up, around, and down the trunks of one or 

 more trees. This habit is not peculiar to the Tahoe Chipmunk, but is 

 indulged in by most, if not all, of the other species. Whether it is pure 

 play, or whether it is part of the courting behavior, we do not know, but 

 its occurrence at various seasons of the year and the fact that young 

 animals often engage in it, indicate that it is not related immediately to 

 mating. As pointed out in the chapter on the Alpine Chipmunk, there are 

 various and diverse relations borne between individuals of the same species, 

 and some of these seemingly mild-mannered chases may, in actuality, ])o 

 instances where one individual has invaded the small area of territory 

 over which some other chipmunk already exercises 'property rights' and 

 is 'defending title.' The study of behavior in chipmunks in a state of 

 nature would prove a fascinating one, and the plentiful population of 

 these animals at easily accessible spots in the Yosemite region affords 

 excellent opportunities for such a study. 



The fact that the Tahoe Chipmunk is the only one of seven local species 

 which habitually climbs high in the trees is a point of evidence that restric- 

 tion to a particular type of habitat or mode of behavior does not always 

 rest upon the possession of conspicuous special structural features of an 

 adaptive nature. So far as can be seen by an examination of specimens 

 in hand, none of the other species of chipmunks is physically incapacitated 

 for tree climbing; in fact, individuals of these others are occasionally 

 observed well up in the trees. There doubtless are minor features of 

 structure, associated with a different psychology, which account for the 

 differing traits indicated. Age-long segregation, in separate areas of differ- 

 entiation, of the several stocks may be the basis of this divergence of habitat 

 preference. The shifting of climatic barriers, Avith the resulting migrations 

 of populations, has thrown the species together as very near neighbors or 

 as actual companions. Fatal competition is prevented as a result of these 

 initial predilections, whereby frater favors the trees, alpinus the rocks, and 

 senex and quadrimaculatus the brush patches and logs. 



A Tahoe f'hipmunk three-fourths grown was eaught lightly by one 

 front paw in a mouse trap at our Lyell Canon canq) in late July, 1915. 

 One of the members of the party kept the animal in captivity for a time 



