628 THE MONTHLY BULLETIN. 



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 com- 

 pletely 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 hill- 

 side; 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, 



