favorable. While our observations show them to be strictly diurnal in habits, we have noted an apparent aversion to direct sunshine. Perhaps this is because the sunshine on the desert is in summer so intense as to be quickly fatal to any small animal exposed to it for long. We know for a fact of squirrels caught in traps by one foot or merely a toe, on open ground, which have quickly succumbed–"sun-cooked" is the
Fig. 23. Diagram showing the ranges of the ground squirrels of California according to life-zones. (For life-zone map of California, see Grinnell, 1913, pl. 15.)
term we use for such victims. At any rate, the squirrels are seen crossing open spaces but momentarily, and thenceforth they remain in the shade of bushes until they take final alarm and descend into their burrows.
The long, slender, ratlike tail is exclusively characteristic of this species of ground squirrel. The body, too, is rather slender, though after a full meal of green stuff individuals have been seen which showed a rather pot-bellied outline. The mere rims of ears give the animal a round-headed look. The movements are rather more agile than in most of its relatives. It not infrequently climbs up into bushes to a height of four or five feet, but here it becomes clumsy.
The voice of the Round-tailed Ground Squirrel is unmistakable when once learned. As far as known to us, but one kind of note is uttered, a single high-pitched squeak or shrill whistle, seep, uttered only at rather long intervals, never in a series as with some others of the ground squirrels. The quality of this call is such that the direction from which
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