Page:Natural History of the Ground Squirrels of California.djvu/63

Rh few. To the westward they extend within a mile of the seacoast in the vicinity of Eureka and at Cape Mendocino, but elsewhere mostly not closer to the sea than eight or ten miles. Nowhere in the immediate coast belt are they reported especially numerous or injurious. Pocket gophers there loom up as the most destructive rodent.

The voice and mannerisms of the Douglas Ground Squirrel are not to us in any points that can be remembered materially different from those of the California Ground Squirrel. A fair test of this could, of course, only be made upon the two if studied side by side under perfectly normal conditions. In the nature of the case this is impossible, for in no known locality do they occupy common ground.

The tail is at all times the most conspicuous feature of this ground squirrel. Sometimes when running to its burrow a squirrel will hold its tail in a continuously vertical position, or this member may be thrashed fore and aft. Ordinarily the tail is held nearly parallel to the ground, with more or less of an arch in it. In this posture of tail one is reminded strongly of the Gray Squirrel.

Our own observations, and the testimony of people in general who are familiar with several of our ground squirrels including the Douglas, indicate that the latter is the most prone of all to climb trees. For instance, near Tehama, June 8, 1912, several individuals were seen well up in large white oaks (W. P. Taylor, MS). At Winslow, Glenn County, June 19, 1912, one was seen in a buckeye, and several from twelve to fifteen feet above the ground in willows and cottonwoods (W. P. Taylor, MS). At Sisson, Siskiyou County, August 11, 1914, one was seen thirty feet above the ground in an incense cedar (T. I. Storer, MS). It is a common thing to see them perched upon the tops of fence posts or stumps. Individuals may under certain circumstances so nearly resemble Gray Squirrels as to be actually mistaken for them. This emphasis of the tree-climbing habit in the Douglas Ground Squirrel is, suggestively enough, thus associated with greater length of tail and grayer tone of color of tail, as compared with its nearest relatives. It seems, also, that this species, more generally than any other, raids orchard trees such as almond and apricot.

The sure test, on the basis of behavior, of a ground squirrel as compared with any true tree squirrel, such as the California Gray, is that the former, no matter how high in a tree when discovered, will, upon alarm, take to the ground as quickly as possible, and seek safety in a burrow below ground, rather than make off through the branches from tree to tree, or ascend into the uppermost foliage of a treetop. Not infrequently, when surprised in a tree, a ground squirrel will for the time being "freeze" and attempt to escape being seen by remaining motionless. But after being further disturbed and once starting, he makes for the ground by the shortest route.

The burrowing habits of the Douglas Squirrel are similar to those of related species. Steep banks seem to be chosen for burrowing into, whenever available. Many burrows open under rocks, bushes and tree roots. On open, level ground, with no protective shelter at hand, the mouths of the burrows are marked by good-sized mounds, showing the presence of an extensive system below ground. As far as we know, no one has yet made a complete excavation of the burrow system of this species.