Page:The Common Ground Squirrels of California.djvu/4

 of one of these animals. The real danger of the spread of infection lies in the dissemination of infected fleas. As has been shown by the recent campaign against these ground squirrels, carried on by the U. S. Public Health and Marine Hospital Service, eradication of this pest depends largely on persistent work of the individual.

This group of long-eared gray ground squirrels has a wide range, being found throughout the State. Several species and several varieties of each have been recognized. Each variety or subspecies occupies a fairly well-defined region of the State, so that they can usually be distinguished by the locality in which they are found. The northern coast form is known as the Douglas ground squirrel (Citellus douglasi) that of the interior valleys, as the California ground squirrel (Citellus



FIG. 1. Two varieties of the common "digger" ground squirrel of California, found throughout the State. The squirrel above is the Douglas ground squirrel (Citellus douglasi), found along the coast north of San Francisco Bay; the one below is the California ground squirrel (Citellus beecheyi beecheyi), the common ground squirrel of the interior valleys and the carrier of bubonic plague.

beeckeyi beecheyi); and that of southern California, as the Fisher ground squirrel (Citellus beecheyi fisheri).

In the extreme northeastern corner of the State and to some extent in the northern part, a smaller brown ground squirrel is found in abundance. It is known as the Oregon ground squirrel (Citellus oregonus). The ground squirrel of the desert is much smaller than the common "digger" squirrel and is striped. It is called the desert or round-tailed ground squirrel (Citellus tereticaudus). A small striped form belonging to another genus (Ammospermophilus) is found to a limited extent in the San Joaquin Valley, and a variety of the same species in the rocky places in the deserts and foothills bordering the deserts. These forms are known as the Nelson ground squirrel and the Antelope ground squirrel. Neither are abundant enough to be of great economic importance. Golden-mantled ground squirrels (Callospermophilus sp.), more often called red-headed chipmunks, are mountain species and seldom give trouble (Fig. 2).