Page:Natural History of the Ground Squirrels of California.djvu/62

646 they overlap, or, indeed, as far as known, quite meet. Roughly, the Douglas Ground Squirrel occupies the northern and northwestern third of the state.

The local or habitat preference of this species is more exclusively for hilly country than in the case of the California Ground Squirrel. It is true that the Douglas exists out on the floor of the Sacramento Valley nearly to the lands annually flooded along the river; but it occurs there interruptedly, in far separated "colonies," and never anywhere are the great numbers reached that characterize beecheyi in the San Joaquin Valley. The preferred haunts of douglasii are the openings or glades on hillsides, beneath scattered oaks or pines, or else the open tracts along stream courses, not, however, quite down to the water's edge. The edges of the smaller valleys between the coast ranges are well populated, but the open floors of these valleys are not often invaded very far or in any considerable numbers. Dense chaparral and thick woods are avoided altogether.

It is interesting to note here that where the coast redwoods have been lumbered out the Douglas Ground Squirrels have come in from the interior so as to be plentiful where formerly scarce or wanting. Chaparral slopes which have been swept by fire are also quickly invaded and occupied for a time, until the brush grows up thickly again. It is probable that the squirrels are unable to maintain themselves against enemies, such as bobcats, that habitually hunt by stealth through underbrush; the squirrels require a certain amount of space around them so that they can have a fair show of reaching the safety of their burrows after an enemy is first caught sight of. Even though the Douglas Ground Squirrels are nowhere so very numerous as compared with certain other rodents, their predilection for clearings brings them into economic prominence locally. We have been told repeatedly of cases where newly cleared farms in mountain valleys have been invaded at harvest time from the nearby hillsides, to the almost complete loss of the crops.

It is a curious thing that the Douglas Ground Squirrel should not occur south clear to the shores of San Francisco Bay, inasmuch as the Beechey on the south side of the bay extends up to either the very shore line itself or to the margin of the salt marshes adjacent, or did so until very recent years. This may be merely another indication of the lesser degree of aggressiveness or prolificness on the part of the Douglas Squirrel. Marin County seems to be devoid of any ground squirrels whatsoever, except for a few douglasii along the Sonoma County border. Joseph Mailliard (interviewed on May 8, 1918) states that in his forty years or more of residence in Marin County, he never saw any ground squirrels in the southern part or westwardly towards Point Reyes. Individuals were seen twice many years ago on the Rancho San Geronimo, but "they never stayed." To all appearances the conditions here are identical with those in the Russian River district and a few miles west of Petaluma where the animals in question are plentiful, or used to be until successfully combated.

Within the California portion of its range the Douglas Ground Squirrels are believed to be most numerous in Tehama County, this according to the consensus of opinion in the office of the State Superintendent of Rodent Control. In Shasta County, next on the north, there are