THE GROUND SQUIRRELS OF CALIFORNIA. 



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The nests were generally at the intersections of the burrows and were 

 made of wild grass blades and stems and blades of grain. The brood 

 nest was larger than the ordinary summer nest and was lined with 

 finely shredded nest material. 



BREEDING. 



Very shortly after coming from hibernation the squirrel begins to 

 breed. The season of rutting is a very active one and is followed by 

 a gestation period of 24 days. When the young are born they are very 

 imperfect little animals, being naked, blind and toothless (Fig. 34). 

 Their subsequent growth is rapid and in about five or six days they 

 have doubled their original weight (Fig. 35). By 12 days their bodies 

 are covered with a dark silky hair (Fig. 36) and by 17 days (Fig. 37) 

 their eyes are beginning to open preparatory to coming out of the den 



F'ig. 34. Young squirrls only a few hours old. When born they are very imper- 

 fect, being blind, toothless, and hairless, and weigh between seven and eight 

 gram*. 



into the sunlight, which they do at about 21 to 24 days. By 28 days 

 they are out and ready to leave the brood nest and shift for themselves 

 (Fig. 38). 



At this stage in the growth of the animal, the life history seems to 

 be influenced by climatic conditions, for already two of the five months 

 of activity of each year has been used up and the young squirrels have 

 to accumulate enough fat to carry them through the adverse season 

 of aestivation and hibernation. Accordingly, growth seems to be sus- 

 pended temporarily, to be taken up and completed the following spring. 

 Figure 39 shows a wild brood in their nest. There is but one brood 

 per year. 



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