THE GROUND SQUIRRELS OP CALIFORNIA. 609 



on the campus at Berkeley, that were plainly caused by the presence 

 of squirrel burrows which had concentrated and conducted the water 

 in narrow channels instead of permitting it to spread out and soak in 

 or run off in the natural way. The presence of squirrels along irriga- 

 tion canals results in the embankments becoming undermined by their 

 burrows, with ensuing disastrous breaks in the canals, especially at 

 times of high water. 



Digger Squirrels are firm believers in the daylight saving plan. 

 Their activities above ground are restricted to the hours between sunrise 

 and sunset. They love the warm sunshine and may often be seen 

 sprawled upon the summits of stumps, rocks or other points which 

 afford safety as well, basking in the morning or later afternoon sun- 

 shine. During spring and summer they come out of their burrows soon 

 after sun-up. They are at those seasons most active during the middle 

 of the forenoon and again during the late afternoon, but avoid the 

 intensest heat of midday. During midwinter those squirrels which do 

 not remain underground altogether make their appearance only late in 

 the forenoon of bright sunny days. Light and warmth seem to be 

 essential to their successful existence aboveground. 



The observer afield often comes upon ground squirrels which are 

 some distance from their holes. Such animals usually run, with bodies 

 and tails undulating and closely paralleling the ground, to the near 

 vicinity of their burrows, where they then post themselves in upright 

 position. They can then watch the intruder, yet be in readiness to 

 dart down into their holes at an instant's warning. "While thus on 

 watch a squirrel is wont to repeat, at regular intervals of from two to 

 five seconds, its characteristic ''bark." This note is really a double 

 one, and may be indicated by the syllables, clink-sup. The second 

 syllable, however, is not audible for any great distance, while the first 

 is loud, staccato, and of decided metallic quality, calling to mind the 

 sound produced by the blow of a light hammer on an anvil. The im- 

 pression is enhanced by the regularity and frequency of its utterance, 

 and this will be kept up five minutes at a time. Sometimes, when a 

 squirrel is startled, it gives a more prolonged note, clink-sup-sup-sup- 

 sup, the last syllables running together as a sort of chuckle. In any 

 event, it is the clink which is the metallic syllable, and which one hears a 

 long ways, more or less mellowed by distance. 



If closely pressed the squirrels drop down at once into the protection 

 of their subterranean retreats. Ordinarily when thus frightened down 

 they do not reappear at the surface of the ground for some minutes, 

 five to twenty-five minutes in tested cases, as if to give the suspected 

 enemy a chance to tire of his waiting and depart. Occasionally, when 

 surprised at a distance from its burrow, a squirrel will crouch motion- 

 less, it may be almost at the feet of the oi)server, as if to escape detection 

 by the "freezing" ruse. Extreme fear also on occasion may be part 

 of the basis for this mode of behavior. 



In some respects the California Ground Squirrel is much "wiser" 

 than is generally supposed. This has been forcibly impressed upon 

 the junior author during his endeavors to secure photographs. Living 

 squirrels were then observed at close range in their various activities 

 under natural conditions. Several species of chipmunk, as well as the 

 Golden-mantled Ground Squirrel and the Nelson Antelope Ground 



2— 43C0T 17 



