OBSERVATIONS ON THE HIBERNATION OF GROUND 
SQUIRRELS 1 
By William T. Shaw 
Zoologist, Washington Agricultural Experiment Station 
INTRODUCTION 
While making observations on the life history of the Columbian 
ground squirrel (Citellus columbianus columbianus) difficulty was ex¬ 
perienced in obtaining data on the hibernation. Information on this 
subterranean phase of the animal's life cycle was obtained, however, 
by patient and long-continued search and excavation in the field. 
But there still remained many hidden and obscure points, especially 
in regard to the day-by-day activity of the animal while in the state 
of aestivation and hibernation, which could be learned only by ob¬ 
servations repeated continuously during the entire period of coma. 
To make these observations possible it was necessary to have the 
animals under partial and absolute control. This was accomplishd 
by carefully planned and properly constructed yards for observations 
of a semirestricted nature and a cabin and hibernation cellar for 
closer and more detailed observations. For the purpose of the 
former, the undisturbed dens of wild squirrels were securely fenced 
in. 2 For the latter, a cabin (fig. 1) was constructed with which were 
connected small yards and beneath which was a cellar furnished with 
small compartments in which aestivating and hibernating squirrels 
could be placed and be easily observed, day or night, at the will of 
the observer. With this equipment, wild squirrels were obtained 
from the fields and the work was begun, with the following results. 
As might have been expected, the sudden transfer from wild to 
captive life caused the squirrels to break the regularity of their life 
routine, and it was usually some weeks before they overcame their 
fear of the new surroundings and went into the comatose condition. 
Indeed, if food were continually furnished them they would some¬ 
times remain awake during the entire winter. 
To induce them to go into hibernation, food of fattening properties, 
such as they were accustomed to obtain under wild conditions, was 
approximated in the form of a sheaf of wheat or oats and the seeds 
of sunflowers. Moisture was given in the form of carrots and apples, 
of both of which they are very fond. 
Besides those placed in the hibernation cabin, others were confined 
in the yards of a nearby brood cabin used for determining other phases 
of the life history. Here, as in the former place of confinement, they 
usually dug small dens in the accompanying yards and there trans¬ 
ferred the nest. This was desirable, as it removed them from the 
effect of the unnatural condition of midday heat in late summer and 
1 Received for publication Dec. 13,1924; issued December, 1925. Published with the approval of the 
Director of the Washington Agricultural Experiment Station as Scientific Paper No. 112, College of Agri¬ 
culture and Experiment Station, Pullman, Wash. 
* Shaw, W. T. a life history problem and a means for its solution. Jour. Mammal. 6:157-162, 
illus. 1925. 
Journal of Agricultural Research, 
Washington, D. C. 
( 761 ) 
Vol. XXXI, No. 8 
Oct. 15, 1925 
Key No. Wash. -6 
CEREAL INVESTIGATIONS. 
