THE GROUND SQUIRRELS OF CALIFORNIA. 693 



the last week of May are numerous. The latest date is September 4 

 (1908) for half -grown young at Vallevista, San Jacinto Valley. From 

 all the facts at hand we would estimate the usual date of birth for this 

 species to be close to May 10. 



By the time they are half grown the young seem to be well able to 

 forage for food by themselves. No solicitude has been observed on the 

 part of the parent. The young show themselves to be less shy than 

 adults, and for this reason it is probable that a large toll is taken by 

 their enemies during early summer, until the young get sophisticated. 



The Antelope Ground Squirrel, according to the data above given, 

 is the most prolific of all our species of ground squirrels. It can be 

 inferred from this that existence on the desert, in the mode followed 



Fig. 27. Desert Antelope Ground Squirrel, about one-fifth grown, found wandering 

 about weakly under a mesquite at Furnace Creek Ranch in Death Valley, April 23, 

 1917. Photographed by J. Dixon. Although very young and feeble this little squirrel 

 persisted in holding its tail at all times over its back in characteristic Ammospermo- 

 philus fashion. 



by this squirrel, is the most precarious. The factor of high mortality 

 must therefore be provided against by high birth rate. The category 

 of predaceous animals which occupy the same territory and which are 

 sure to prey habitually upon the Antelope Squirrel includes "snakes, 

 weasels, foxes, coyotes, badgers, bobcats, and many kinds of hawks" 

 (Nelson, 1918, p. 443). 



At all the lower elevations, where the winters are not especially cold, 

 Antelope Ground Squirrels are to be seen abroad at all seasons. For 

 instance, around Victorville in December and January, 1904-05, and 

 at Palm Springs in December, 1904, they were to be seen nearly every 

 day, though they did not seem to be foraging far and wide actively 

 then as is their wont in March and later. At the former locality on the 

 coldest windy days none was seen. It is very likely that at higher 

 places, altitudinally, especially where there is some snow, as at the head 

 of Owens Valley, these animals hibernate through the coldest months. 



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