766 
Journal of Agricultural Research 
Vol. XXXI, No. t 
of his box closed he acted philosophically and postponed starvation 
by returning again to hibernation. On February 14 it was found 
that he had been gnawing in an effort to get out, so he was given his 
liberty. On this date he was fully awake and came out into the 
snowy yard and ate some carrot (fig. 3). 
On coming from hibernation permanently they soon repair their 
nest. This is done by piling up the material in a neat, fresh, warm¬ 
looking structure suitable for an active life. 
DURATION OF HIBERNATION IN THE LARGE YARDS 
In the winter the large dens of the yards were used for hiberna¬ 
tion studies. It was found that the duration of hibernation for two 
males was 169 and 131 days; for 4 females, 190, 178, 178, and 179 
Fig. 3. —Yard observations. In the cellar, it was possible to observe squirrels daily the winter 
through, thus enabling comparison of these conditions with field conditions. This squirrel (a 
Townsend) slept almost continuously for eight months. He awoke at about the normal time, 
but, not finding food, went back to sleep 
days; for 2 young, 209 and 233 days. Of course, conditions were 
not normal, as in the fields, and the squirrels were slow in going 
into hibernation. The young, being tamer, went first. As in the 
fields, the duration of hibernation is greater among the females 
than among the males, and in one case the female returned from 
hibernation 15 days later than the male. One male lost 123 grams 
in 169 days or 0.7 gram per day. 
TEMPERATURE OF BOXES 
Nine daily records taken between August 14 and September 9, 
1912, showed that the summer temperature of the boxes was much 
more constant and favorable to aestivation, varying only 7 degrees, 
against a 35-degree range of air temperature and averaging 15 
degrees lower than the air. A hibernating squirrel can resist a 
