The breeding season is indicated by the time of appearance of the young aboveground. In Scott Valley, Siskiyou County, where the species is abundant, very small young were seen abroad on June 8 (1911). At Winslow, Glenn County, young one-fourth to one-half grown were captured on June 16 (1912). At 6,800 feet altitude on the Saloon Creek Divide, in the Scott Mountains, Siskiyou County, July 10 (1911), nursing females were captured, but no young were yet out (L. Kellogg, MS). It is thus probable that at the lower altitudes the young are born during the last half of May, while at the highest levels they are not born until at least a month later. Only one litter is reared each year.
Unfortunately we have no facts of our own to offer in regard to size of litter. We have an idea that fewer young are born each year than in the case of the California Ground Squirrel, judging roughly from the numbers of young seen aboveground, about five. But this is almost pure conjecture. F. E. Garlough, of the United States Biological Survey, is under the impression (interviewed September 7, 1918) that litters in the lowlands average close to eight, while, in the mountains five is the usual number. He has known of as few as two and as many as fourteen embryos having been found in pregnant females.
The following definite data on file in the Museum of Vertebrate Zoology show some of the kinds of food selected by the Douglas Ground Squirrel and also the quantity in which each of these kinds may be gathered at one time. A male squirrel taken on Dry Creek where crossed by the Oroville-Chico road, in Butte County, May 31, 1912, contained in its cheek pouches 29 seeds of a wild lupine (Lupinus micranthus). Three others taken on Butte Creek, near Chico, June 3 and 5, 1912, contained in their cheek pouches materials as follows: male, 12 seeds of milk thistle (Silybum marianum); female, 219 grains of barley and one head of English plantain (Plantago lanceolata); female, 142 grains of barley. The cheek-pouch contents of two squirrels taken on Mill Creek, near Tehama, June 12, 1912, consisted of, respectively: female, 121 seeds of bur clover (Medicago hispida) and 70 small unidentified seeds, part loose and part in three whole pods; female, 181 seeds of brome-grass (Bromus carinatus) and one piece of an acorn. Two squirrels taken in the hills three miles west of Vacaville, July 3 and 6, 1912, contained in their cheek-pouches: female, 29 seeds of Napa thistle (Centaurea melitensis) and 30 seeds of bur clover; male, 82 seeds of bur clover, 4 seeds of Napa thistle and one cherry pit. A male taken three miles south of Covelo, Mendocino County, July 20, 1913, held in its cheek-pouches 14 whole fruits and 103 separate seeds of the common manzanita (Arctostaphylos manzanita), as also a few small unidentified seeds of two kinds.
From all sources comes the testimony that this species takes barley and wheat with particular avidity. Its storage propensities are highly developed, and it would be interesting to see actual figures as to the quantity of grain garnered underground in one autumn season. Where they invade apricot orchards, as in the foothill district of the Warner Mountains near Alturas, these squirrels climb the trees and take out the pits, discarding the pulp of the fruit.
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