Page:Natural History of the Ground Squirrels of California.djvu/93

Rh bring the animals out into full activity. "I caught sight of one standing upright at the mouth of its burrow, squeaking, and of two others running over the sand beneath the trailing green mesquite branches. The lines of footprints in the sand centering at the mouths of their burrows are diagnostic. The animals are extremely shy, going below ground at the slightest alarm. By standing ten minutes or so 'at attention' about fifteen yards from the mouth of a burrow down which one vanished, I finally saw the top of its head reappear to the level of its eyes. This position was maintained for many minutes, until the animal suddenly raised its whole head and neck into view, when I shot it.

"Later, while I was lying prone on the sand under a mesquite, one came up to within eight feet of me and gave its shrill, wiry cry, or squeak. A mere movement on my part, and it vanished, quick as thought." It was found that a little "screeping" (lips to back of hand) would often bring one of the squirrels stealthily investigating through the brush, provided the observer kept perfectly motionless himself and was possessed of patience. The squirrel would sometimes squeak, apparently in answer, and thus be called into very close "aux" range. The burrows were as a rule located in the periphery of a large mesquite clump, where they were shaded by the radiating leafy branches which trailed down the sandy slopes. Not more than three burrows certainly of this rodent were to be found about any one clump.

The mesquites during early April were just coming out into full new foliage. The stomachs of the squirrels shot were distended with masses of finely chewed mesquite leaves and nothing else. This, in fact, was absolutely the only kind of vegetation anywhere in sight for hundreds of yards. In one instance the total weight of the freshly killed animal was found to be 154.5 grams; of the full stomach alone, 28.7 grams, or 19 per cent (near one-fifth) of the total weight. In other words, a Death Valley Round-tailed Ground Squirrel may eat close to one-fourth its own weight of green mesquite leaves.

No young were seen by us up to the time of our departure, but they are probably born about the first of May. Two old females captured April 10 and 12 contained four and three embryos, respectively.

Other names.—Pale Spermophile; Citellus chlorus.

Field characters.—Exactly as for the Yuma Round-tailed Ground Squirrel.

Description.—As for the Yuma Round-tailed Ground Squirrel, but tone of coloration more grayish, avellaneous rather than light pinkish cinnamon. This difference holds through all pelages and gives the impression of an olive-colored animal, when close comparisons are made with series of the other related ground squirrels.

Color variations.—Specimens showing the spring molt to be in process bear dates from March 29 to as late as June 3. As with the other races of tereticaudus the pelage on the tail is not replaced during the spring molt and it becomes greatly faded and worn. In extreme cases the tail with its shortened, singed-looking hairs is a dirty pale brown color throughout, and as slender as a wood-rat's tail. The summer