THE GROUND SQUIRRELS OF CALIFORNIA. 



701 



The young of nelsoni are apparently all born before the last of April. 

 None of the numerous females taken in the vicinity of Bakersfield 

 between April 27 and May 12 were found to contain embryos. A male 

 one-fourth grown was taken eight miles northeast of Bakersfield on 

 May 7, 1911, and a half-grown young one was taken at McKittrick on 

 May 18, 1911. On May 9, 1918, two immature individuals, weighing 

 100 and 103.3 grams, respectively, were taken at the mouth of San 

 Emigdio Creek. These, male and female, were thus over two-thirds 

 grown and were at this time foraging for themselves. These two 

 youngsters were extremely playful and on several occasions they were 

 seen to stand upon their hind legs and with their front paws braced 

 against one another's shoulders they wrestled and pushed each other 

 about energetically. The parents of these young squirrels had evidently 

 cast them off to shift for themselves. 



Because the California and Fisher Ground Squirrels have increased 

 and profited by the farming activities of man in parts of the San 

 Joaquin Valley, it has been suggested that possibly this increase has 

 tended to crowd out Ammospermophilus nelsoni and therefore restrict 

 the range of the latter (Taylor, 1916, p. 20). At the mouth of San 

 Emigdio Creek both nelsoni and fisheri were found in numbers. Old 

 colonies of fisheri, as shown by their extensive workings, were found 

 between colonies of nelsoni. The Antelope Squirrels occupied the 

 sandy washes and the areas covered by the salt-bush, while the Digger 

 Squirrels occupied the more open tracts which were covered by a low 

 growth of foxtail. While there must be a certain degree of competition 

 as regards food supply between the two kinds of squirrels, this com- 

 petition is probably no greater than that which exists between the 

 Nelson Antelope Ground Squirrel and, for example, each of the two 

 species of kangaroo rats which forage at night for similar food over 

 the same ground used by the Nelson Squirrels in the daytime. We 

 found no evidence, in this case, that the Digger Squirrels were driving 

 out the Antelope Squirrels. 



The badger is one of the chief enemies of the Nelson Ground Squirrel. 

 Many squirrel burrows were found that had been dug out by this animal, 

 and, since in their refuge burrows these squirrels have no back door 

 of escape, capture in such cases must be more or less certain. 



On May 19, 1918, a pair of Nelson Squirrels was observed to remain 

 out in the open and watch a pair of Golden Eagles go through a series 

 of aerial evolutions overhead, in which, with talons tightly locked 

 together, the birds looped the loop three times. The eagles were 

 obviously seen by the squirrels, and the swish of their wings was 

 plainly heard by the observer, yet the squirrels were not in the least 

 alarmed. However, when a Red-tailed Hawk flew over, the squirrels 

 hustled at once into their holes. It was therefore inferred that the 

 hawks and not the eagles were the active enemies of these small squir- 

 rels. Coyotes and kit foxes also dig out the squirrels in their burrows 

 and probably pounce upon a few individuals during the daytime. 



In foraging, these squirrels slip along close to the ground, often 

 stopping in the shelter of a bush or pausing in the open and searching 

 quietly, with body extended, for small seeds upon which they feed. On 

 May 6, 1918, an old female which was nursing young was observed for 

 several minutes at a distance of fifty feet. During this time the squirrel 

 stood at her full height with body erect, busily munching a green head 



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