THE GROUND SQUIRRELS OF CALIFORNIA. 



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The Douglas, as is known of most other ground squirrels, is fond of 

 flesh when this can be obtained. Many have been taken in the meat- 

 baited steel traps kept out in various localities for carnivores. 



Hibernation seems to be more prevalent with douglasii than with 

 beecheyij for all of the population of the former is reported to disappear 

 for weeks at a time, even in the lower valleys. At the higher altitudes, 

 where there is more or less heavy snow, all the squirrels disappear over 

 a period of some months. In Hayfork Valley, Trinity County, the 

 senior author was assured by several different people living there that 

 the Douglas Squirrels hibernate regularly and completely "from Novem- 

 ber till April. ' ' The earliest spring record we have for a mountainous 

 region is of one squirrel caught in a box trap February 25 (1911) near 

 Helena, Trinity County (A. M. Alexander, MS). 



The natural enemies of this squirrel probably include practically all 

 those already specified in our chapter on the California Ground Squir- 

 rel. Only one specific instance is at hand. A gopher snake found 

 run over in a road near Chico, June 7, 1912, was found to contain in its 

 stomach a young Douglas Ground Squirrel (T. I. Storer, MS). 

 Coyotes are locally reputed to levy considerable toll upon this rodent. 

 We have heard the argument advanced against the poisoning of ground 

 squirrels on wild mountain land in the northwest coast district that 

 reducing the squirrel population will deprive the coyote of one of his 

 chief sources of subsistence and that he will thereupon be forced to 

 seek food elsewhere and so be more prone to raid the poultry of the 

 valley ranches and the flocks of sheep in the mountains. On the other 

 hand, it may be advanced that the total coyote population is adjusted 

 to the total amount of food available at the season of least supply, and 

 that removal of any one important kind of food will in course of time 

 reduce the total coyote population able to exist in any general territory. 



A high natural mortality for this species may account for its relative 

 lack of aggressiveness as compared with the California Ground Squirrel. 

 The testimony of a number of people from localities widely scattered 

 over the range of the Douglas Ground Squirrel is to the effect that 

 every few years there is a great reduction in its numbers. Some fairly 

 close observers, forest rangers in the Trinity region, for instance, think 

 this is due to the effects of severe winter weather, as when there is an 

 exceptionally heavy snowfall or torrential rains of unusual amount. 

 In either case the squirrels are thought to be drowned in large propor- 

 tion when lying dormant underground. Other persons think there are 

 recurrent epidemics of some disease fatal to the ground squirrels. "We 

 have no good evidence bearing upon either hypothesis. 



Because of this observed reduction in numbers during some winters, 

 certain ranchers have objected to carrying on poisoning operations in 

 the fall, since their efforts might prove to have been unnecessary. 

 They prefer to deal with the naturally reduced squirrel population of 

 the springtime, at the close of the dormant period. 



The general range of the Douglas Ground Squirrel has not changed 

 within history as far as definite records show. But, locally, there have 

 been marked fluctuations. On the western side of the Sacramento 

 Valley the animals have been almost completely cleaned out on many 

 large tracts as a result of systematic poisoning. This is particularly 

 true, as we are assured by W. C. Jacobsen, State Superintendent of 



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