630 



THE MONTHLY BULLETIN. 



1 to 38 (1 to 50-1 to 22). The stomach contents in these cases con- 

 sisted almost entirely of finely chewed seeds of barley and bur clover. 

 The squirrels were shot between noon and 2 p.m. Seven full-grown 

 males taken on August 15, 1918, near Walnut Creek, gave an average 

 total weight of 659.4 (576.8-724.7) grams each; the average weight of 

 the stomach contents was 17.9 (11.5-20.5) ; and the average ratio of 

 contents of stomach to total weight was 1 to 37 (1 to 63-1 to 30). 

 Seven full-grown females taken at the same time and place gave an 

 average total weight in grams of 500 (370.7-681.4) each; the average 

 weight of the stomach contents was 9.7 (5-15.8) ; and the average ratio 

 of contents of stomach to total weight was 1 to 42 (1 to 101-1 to 37 ) . 

 All these fourteen squirrels were foraging in stubble fields, and the 

 stomach contents consisted of barley and bur clover seeds finely chewed 

 and of nearly the same degree of moistness as ordinary baker's dough. 

 The squirrels were shot between 10 a.m. and noon. 



It is believed by us that two ounces of green forage or one-half ounce 

 of dry grain is an average stomach-full for an average-sized California 

 Ground Squirrel and that two stomach-fulls represent a day's ration. 

 It is evident that the proportion between the weight of the stomach 

 contents and the total weight averages considerably less in this species 

 than it does in the Oregon Ground Squirrel. The California is more 

 of a seed eater and less of a grass eater than the Oregon Squirrel and 

 therefore enjoys a more condensed ration. 



During late summer digger squirrels, particularly the old adults, 

 become exceedingly fat. In this condition they become obviously lazy 

 and may often be seen lounging at the entrances to their burrows sim- 

 ply enjoying the sunshine. As the season farther advances, a decided 

 decrease in squirrel population is noted. The active young of the year 

 are still foraging abroad, but even these restrict their activities to the 

 brightest hours of sunshiny days. "What becomes of the squirrels which 

 have altogether disappeared underground? 



One would naturally expect that the life history of such a notorious 

 animal as the California Ground Squirrel would be known pretty 

 thoroughly. However^ such does not seem to be the case ; there are sev- 

 eral features of the underground life of this squirrel in regard to which 

 our information is very inadequate and of which from the standpoint of 

 rodent control it would be most useful to know. As has been previ- 

 ously mentioned, little appears to be definitely known regarding the 

 period of gestation of this animal. The condition of the young at birth 

 and their subsequent care and development is also not well known. 

 Another moot point is that of aestivation or hibernation of this species 

 of ground squirrel. Merriam (1910, p. 4) states that "this species 

 does not hibernate, except in the mountains, although in the foothills 

 and valleys the animals usually stay in their burrows during stormy 

 and severe weather. At the upper limit of their range, where the 

 ground in winter is covered with snow, they may remain underground 

 long enough to be said to hibernate, but over the greater part of the 

 state they are out in numbers every month of the year." However, 

 we believe we have evidence to indicate that a period of aestivation or 

 hibernation (or the two combined), in other words a state of torpidity 

 initially induced by the heat and dryness of summer, obtains among 

 some at least of the adult ground squirrels even in the lowlands. This 



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