616 



THE MONTHLY BULLETIN. 



colonial burrow that was dug out, three nests were found, of which two 

 were new. The nests were always placed well back in the burrows 

 (see figs. 6, 7), where they would have maximum protection from dig- 

 ging enemies such as coyotes and badgers. The cavities in which the 

 nests were placed were short globular chambers and were usually sit- 

 uated slightly above and to one side of the main run, so that the 

 drainage was away from rather than into the nest. The cavity in 

 which a nest containing a feinale and four small young was found 

 measured 10 inches in length, 9 inches wide and 7 inches high. The 

 nest cavity used by a male squirrel was 12 x 10 x 7 inches (in the same 

 dimensional order), while the two nest cavities in the colonial burrow 

 measured 12x10x8 and 12x12x7 inches, respectively. 



All of the nests found were of similar composition and construction. 

 Finely shredded dry grass blades and roots, and fine stems of foxtail 

 and needlegrass, formed the bulk of the constituent material. The 

 nests were spherical in shape and deeply cupped. The walls were from 



Fig. 10. Nest and female of "digger" squirrel as uncovered after the burrow had 

 been gassed. Excavated on the University of California Campus, Berkeley, April 

 6, 1918. 



two to two and one-half inches thick. The walls of the nest which 

 contained the young squirrels were arched over and met at the top, 

 forming a sort of a canopy. Entrance to this nest was gained through 

 a hole near the top. The material in the walls had been compressed 

 or felted into a thick, warm fabric. The outside dimensions of this 

 nest were 10 x 9 x 7 inches, while the inside cavity measured 6x4x5 

 inches. Compared with that of the female just described, the nests of 

 male squirrels were smaller, had lower walls and were more loosely 

 constructed (see fig. 9). The nests of the males did not completely fill 

 the cavities in which they were placed, as did the nest of the female. 

 A nest occupied by a male measured 8 x 10 x 7 inches outside and 

 4x5x4 inches inside. The three nests in a colony burrow excavated 



24 ' >^ '> : &* 



