green stalks. Several times on following up rustling sounds squirrels were discovered on thick mats of dry fallen tules among the standing green ones and just above the water. One, on being alarmed, jumped into the water with a splash and, although lost to sight, probably reached safety by swimming. Davis "Island," near Mendota, is part of the mainland at low water, but in May, with high water, becomes a true island and with the highest water the ground everywhere is completely submerged. On June 20, 1918, a squirrel was discovered on this island. It jumped from a piece of ground into the water and swam, in much the manner of a dog, to a tree up which it took refuge.
Fig. 15. Metropolis of "digger" squirrels under a small oak on a grain-sown hillside; photographed near Walnut Creek, Contra Costa County, August 15, 1918. Owing to the dryness of the season and to the depredations of the squirrels, the grain on the hill above the oak had been left uncut.
A current report was to the effect that each year at high water ground squirrels are marooned on this island and live for the time being in the big hollow-trunked willows there. This shows that flooding does not necessarily drive out or drown these squirrels in such localities as afford refuges on high ground or in trees.
On wild land, alfilaria, foxtail and bur clover are perhaps the three plants that are eaten to a greater extent than any other of our forage plants. Alfilaria is eaten from the time it appears above ground until it ripens, and even after that, when the seeds have scattered out, they are gathered and either eaten at once, or stored. The long, curled "propellers" are broken off and discarded. In Strawberry Canyon on the University campus, in April, the squirrels were harvesting foxtail and alfilaria on sunny southern exposures where the plants had matured early. Later in the season, during late June and early July, these same squirrels with their families of half-grown young were found to have moved down the hillsides, some 150 yards, to the moister, shady ground near the creek bed where the foxtail was still green, and here they were busily gathering the foxtail heads just ripening on July 6. There is an obvious rotation in the use of the different important plants for food,
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