. California ground squirrels : a bulletin dealing with life histories, habits and control of the ground squirrels of California / [by J. Grinnell, J, Dixon and others]. 718 THE MONTHLY BULLETIN. food residue, passes into that very remarkable and profound deathlike condition of aestivation and hibernation. The securing of data upon hibernation is one of the most arduous tasks facing the investigator. Frequently the hibernating den (Fig. 40) is remote from any surface indication of its presence, and although it is in most cases associated with a summer den, is so completely and thoroughly plugg
. California ground squirrels : a bulletin dealing with life histories, habits and control of the ground squirrels of California / [by J. Grinnell, J, Dixon and others]. 718 THE MONTHLY BULLETIN. food residue, passes into that very remarkable and profound deathlike condition of aestivation and hibernation. The securing of data upon hibernation is one of the most arduous tasks facing the investigator. Frequently the hibernating den (Fig. 40) is remote from any surface indication of its presence, and although it is in most cases associated with a summer den, is so completely and thoroughly plugged off from it as to be very difficult to find. It appears to be made in this way: A burrow is run out from a summer den and a perfectly circular cell is excavated for the reception of the hibernating nest. Often a shaft is started towards the surface of the ground for exit in the spring. This shaft is not completed until winter is past and the squirrel ready to come from hibernation. Den (Z) March IZ,l9llt Pollman,Wask. (C. co/omhionus) Fig. 41. Sectional view of a hibernation den. When the den is opened for spring the earth taken in making the exit shaft is spread along the bottom of the shaft and dumped into the drain. (Fig. 41). Having the cell completed the nest is placed in position, coarse grass on the outside and very finely shredded material in the center, completely filling the cavity. As a last resort the squirrel plugs himself in by digging a drain under the nest and using the dirt taken from this drain to close the entrance to his hibernating den (Fig. 40, D). Thus all connection with the exterior is closed by this earth being firmly tamped into place by the nose of the animal. 126. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original California. State Commission of Horticulture; Dixon, Joseph. [Sacr
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Keywords: ., bookcentury1900, bookcollectionbiod, bookdecade1910, bookyear1918
