In California, where they are generally distributed and extremely numerous over great areas, these ground squirrels are most at home among the wild oats and scattered live oaks on the open slopes of the rocky foothills and thence up through the dense chaparral, scrub oaks, piñon pines, and junipers. Above this they populate many beautiful little valleys in colonies, as well as parts of the splendid open forests of pine and fir. Below they spread out from the foothills among the ranches in the great valleys. Wherever they occur they take heavy toll from the native forage plants, and in cultivated areas their devastations of crops place these spermophiles among the most serious of mammal pests. They are omnivorous, eating insects and flesh on occasion, but feeding mainly on seeds, fruits, and many kinds of plants. The native vegetation in their haunts contains a wonderful variety of food plants, from humble weeds in the valleys to the lordly pines of the Sierra, but most attractive to these rodents are the rich food-bearers brought by the cultivators of the soil. The squirrels gather in great numbers about farms, and in feeding upon alfalfa, wheat, and other grains, grapes, peaches, apricots, almonds, prunes, pomegranates, and a variety of other crops, cause an annual loss to the farmers of California probably exceeding $20,000,000. So serious are their depredations that great sums have been spent in attempts to destroy them with poison. The Kern County Land Company, with vast holdings in the southern end of the San Joaquin Valley, in 1911 spent more than $40,000 for this purpose. This company estimated that the ground squirrels destroyed 20 per cent of the grain crop in great areas, and that twenty of them would destroy enough forage to support a cow through the year. Ground squirrels by choice locate their burrows among slide rock, in crevices among cliffs, under boulders and roots of trees, in ditch or dry creek banks, or under stone walls, fences, or building, but in the parks of the high Sierra, as in the foothills and lowland valleys, they dig holes out in the open with conspicuous mounds at the entrances much like those of prairie-dogs. Well-worn trails lead from one of their burrows to another and away to a distance through the wild oats in the foothills, or in the grain and forage crops of the valleys, and along these the animals travel when foraging or paying social visits. Whenever a large rock, stump, or other prominent object is convenient, they spend hours on the top sunning themselves and keeping a sharp lookout over their surroundings. From these lookout points when they suspect danger they utter a short, shrill, whistling note which may be heard at a long distance and which sends all their neighbors scurrying for shelter. They also have a lower chattering note, uttered about the burrow when resenting an intrusion or when otherwise displeased.