Proceedings of the Vertebrate Pest Conference

The Belding ground squirrel (Spermophilus beldingi) is found in rangeland, pasture, and various agronomic crops. However, its impact on agricultural production has been measured only rarely, e.g., by Grinnell and Dixon (1918) and Sauer (1976, 1977). In California, the effects of the Belding ground squirrel appear to be most severe in alfalfa. The present investigations were conducted to measure the impact of the Belding ground squirrel on alfalfa production in northeastern California. Study areas were established on 7 ranches in Modoc County, where rodent exclosure cylinders were placed in alfalfa fields for 44-71 days during growing season before the first hay cutting. Data from alfalfa production indicated Belding ground squirrels reduced alfalfa production by an average of 1,100 lbs per acre (range: 361 - 2,425 lbs/ac) of first cutting alfalfa. Vegetation consumed is probably a very small part of the assessed damage; loss is due to a composite of trampling, runway development, squirrel mounds, vegetation clipping, and forage eaten.