1 to 38 (1 to 50–1 to 22). The stomach contents in these cases consisted 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 simply 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 several 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 previously 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 æstivation 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 æstivation 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
38
