140 NORTH AMERICAN FAUNA [No. 55 



General tidbits. In, habits as well as structure they are between 

 the arboreal squirrels and the true ground squirrels. They are not 

 good climbers, but occasionally climb trees if no other escape is 

 possible. They are fond of running over logs, stumps, and rocks, 

 or sitting on logs, fences, or some other elevated perch where a wide 

 view is obtained; but their homes are in underground burrows, to 

 which they quickly retreat if alarmed. In disposition they are less 

 nervous and active than the chipmunks, often sitting for a long 1 time 

 without a motion and finally gliding away without a sound or a flip 

 of the tail. 



Their voices are not frequently heard, and the single shrill whistle, 

 or sharp squeak, is so ventriloquial that often it is not associated 

 with the animal. The single call is not frequently repeated, which 

 renders it still more difficult to locate. 



Like all of the true squirrels and chipmunks they are strictly di- 

 urnal, working only during daylight hours, and like the ground 

 squirrels they hibernate for a long period during cold weather. 



Their homes are often among the rocks, either in clefts and cracks 

 in cliffs, or in the open spaces in steep rock slides, masses of talus, 

 or broken rocks. Of their nests, dens, and storehouses under rock 

 cover little is known or even of their breeding and wintering nests 

 in burrows in the ground. Occasionally a nest and food cache is 

 found where dug out by a badger or a bear, but always so messed 

 up as to give little idea of original plan and structure. 



In autumn, usually about the middle of September, or with the 

 first freezing nights, they enter their dens for the winter and do not 

 reappear until some time in May, the dates of entering and emerging 

 from hibernation varying with altitude and weather, as well as with 

 age and condition. The old males become fat and enter hibernation 

 first, the young of late litters remaining out latest to acquire the 

 necessary amount of fat for the winter. 



Breeding habits. The mating season of these squirrels begins in 

 spring soon after they emerge from hibernation, and the young are 

 generally born late in June or early July. There are usually 4 to 6 

 young at a birth, but 7 and 8 have been recorded. The mammae of 

 fully adult females are usually in 5 pairs 1 inguinal, 2 abdominal, 2 

 pectoral but in females only a year old the anterior pair of pectoral 

 mammae are usually undeveloped. Only one litter of young is raised 

 in a year, and these have scant time to grow up and get fat in time 

 to hibernate. In fact many of the later young are not fully grown 

 and not very fat when the snow and cold weather shut them in, and 

 if they come through the winter they are not fully grown or in breed- 

 ing condition the next spring. The young usually begin to appear 

 out of the nest when a quarter or a third grown, late in July at 

 middle altitudes, but near Huntington in the Snake Kiver Canyon, 

 young were collected on May 18 and 19, while on top of the Cascade, 

 around the base of the Three Sisters, no young were found up to 

 July 20. 



Food habits. Voracious and almost omnivorous, these potbellied 

 little semiground squirrels eat almost anything of an edible nature 

 that they can find. Green vegetation, roots, bulbs, seeds, grain, nuts, 

 fruit, berries, mushrooms, meat, fat, bread, rolled oats, or any camp 

 food that they can find, will help to fill up their capacious stomachs 



