SMALLER MAMMALS OF NORTH AMERICA 



451 



winter they are sometimes seen running about 

 over newly fallen snow. One which was dug 

 from its winter quarters in British Columbia 

 the last of November would move about slowly 

 and sleepily if teased, but when left undis- 

 turbed would curl up and go to sleep again. 

 This indicates the difference between the light 

 and often broken hibernation of chipmunks and 

 the deep lethargy which possesses ground 

 squirrels in the North at this time. Toward 

 the southern end of their ranges neither chip- 

 munk nor ground squirrel hibernates. They 

 mate soon after they awake from their winter 

 sleep, and the young, two to five or six in 

 number, are born from April to June. Whether 

 more than one litter is born during a season, 

 is, like many other details concerning the lives 

 of these attractive animals, still to be learned. 



THE PAINTED CHIPMUNK (Eutamias 

 minimus pictus and its relatives) 



{For illustration, see page 441) 



The preceding sketch tells how the Oregon 

 chipmunk, living under a cool, humid climate, 

 in a region of great forests, has responded to 

 its environment by developing dark colors and 

 a robust physique. The painted chipmunk of 

 the Great Basin has given an equally perfect 

 response to entirely different conditions. It is 

 one of the geographic races of a species pecu- 

 liai to the sagebrush-covered plains and hills 

 from the Dakotas across the Rocky Mountains 

 and the Great Basin region to the east slope 

 of the Cascades and the Sierra Nevada. Its 

 home is on treeless plains, in a climate, char- 

 acterized by brilliant sunshine and clear, dry 

 air. In this environment the painted chipmunk 

 has developed a smaller and slenderer body 

 than the Oregon species, and strikingly paler 

 colors. 



These differences in physique are accom- 

 panied by equal differences in mental and 

 physical expression. These little animals are 

 exceedingly alert and agile, darting through 

 dense growths of bushes with all the easy grace 

 of weasels. When running they hold the tail 

 stiffly erect. When alarmed they utter a shrill 

 chippering cry, especially when darting into 

 shelter. They also have a chucking call, uttered 

 at intervals, which may be used merely as a 

 note of sociability or to put their neighbors on 

 the alert. 



Although one of the most distinctive animals 

 of the sagebrush plains, this chipmunk also 

 ranges into the borders of open forests on the 

 mountain sides. It is most numerous on flats 

 and foothill slopes among heavy growths of 

 sage and rabbit brush. When its territory is 

 invaded by settlers it does not hesitate to gather 

 about the borders of fields and even to raid 

 barns in search of grain and other food. Its 

 burrows are dug under large sagebrush and 

 other bushes and under rocks and similar 

 shelter. 



As with others of their kind, painted chip- 

 munks habitually gather seeds of many plants 



and carry them in their cheek pouches to their 

 underground dens. In addition to seeds and 

 green vegetation, they eat any fruits growing in 

 their haunts, and also many insects, especially 

 grasshoppers and larvae. In one locality in 

 Nevada during June and July more than half 

 their food consisted of a web worm and its 

 chrysalids with which the sage bushes swarmed. 

 The chipmunks climbed into the bushes and 

 pulled the larvse from the webs. As half the 

 bushes were infested, the work of the many 

 chipmunks had a material effect in reducing 

 the numbers of this pest. The vegetable food 

 eaten includes the seeds of Ribes, Kuntzxa, 

 Sarcobatus, pigweed, and many other weeds, 

 serviceberry, various grasses, oats, wheat, and 

 the seeds of small cactuses. They regularly 

 climb into the tops of large sage and other 

 bushes for their seeds and the ground beneath 

 is often covered with the small sections of 

 twigs cut by them. They climb readily and 

 often travel from bush to bush through tall 

 thickets like squirrels in tree-tops. On warm 

 mornings after frosty nights they may be seen 

 in the tops of the bushes basking in the sun. 



Throughout most of their range they begin 

 hibernation in September or October, and re- 

 appear early in spring. The young appear a 

 month or more later, and litters containing 

 from two to six may be born throughout the 

 summer, indicating the possibility that several 

 litters may be born to the same pair in a sea- 

 son. 



So alert and shy are they that even a person 

 in their haunts day after day will see but few 

 of them. Their hearing is extremely acute, and 

 even at a great distance the footsteps of an in- 

 truder sets them all on the alert. On every 

 side they run swiftly to cover before the ob- 

 server has opportunity to see them. In such 

 places a large setting of baited traps will re- 

 veal their presence in surprising numbers. In 

 one locality, during a brief visit, traps set 

 among the brush for other small mammals 

 yielded more than forty chipmunks. 



On stormy and cloudy days, especially if the 

 weather is cool, painted chipmunks remain in 

 their dens, but on mild sunny days they frisk 

 about with amazingly quick darting movements. 

 A horseman riding along a road leading 

 through a sagebrush flat will frequently see 

 them racing across the road often several hun- 

 dred yards away, the sound of the horse's foot- 

 falls having alarmed the chipmunks over a 

 wide area. Here and there one may be seen 

 climbing hastily to the top of a tall bush to 

 take a look at the cause of alarm before finally 

 seeking concealment. When pursued among 

 the bushes they often run considerable distances 

 before taking refuge in a burrow. When hard 

 pressed they will enter the first opening en- 

 countered, but if it is not its own home the 

 fugitive soon comes out and scampers away, 

 apparently fearful of the return of the owner 

 or perhaps owing to his presence. 



Apparently, as in the case of many other 

 desert mammals, the painted chipmunk, with its 

 related races, is able to subsist without drink- 



