Energy Requirements and Diet of the California Ground Squirrel

Abstract

Oxygen requirements of the California ground squirrel (Spermophilus beecheyi fisheri) are 0.75 ml/g/h. A ground squirrel's daily maintenance requirements are 92.40 cal/g/day. Ground squirrels absorbed 83 percent of the dry matter in forage and 91 percent of the dry matter in oat groats. Forbs other than legumes were the most prevalent forage plants on the study area. Although legumes made up over 50 percent of the ground squirrel's diet in March and April, nonlegume forbs were the major part of the animal's diet. A ground squirrel population of 8.4/ha required in February, March, and April as estimated 0.6, 0.4, and 0.2 percent, respectively, of the forage plants available. During the green forage season, ground squirrels and cattle feed largely on different plant species. J. WILDL. MANAGE. 42(2):373-382 The California ground squirrel traditionally has been considered a serious pest on annual-plant rangeland (Grinnell and Dixon 1918, Fitch and Bentley 1949, Howard et al. 1959) and millions of acres are treated annually in California with various toxicants to suppress its populations. Justification for control often is based on work conducted at the San Joaquin Experimental Range, Madera County, California by Fitch and Bentley (1949) and Howard et al. (1959). They suggested that the California ground squirrels competed with livestock primarily during the green forage season. At the San Joaquin Experimental Range we studied energy relationships in a population of S. b. fisheri during the green forage season and conducted diet studies throughout the